are there any mechanics out there??

[twowheelsprefered]

lookin for a good dependable airhead mechanic in or around zip98531 near tacoma, wa who wont charge me 100$ a frickin hour to help me figure out/ fix my bike. if you are out there and are interested please call me 253 414 8732. thanks...rob

[20774]

There's a few people who are from that area that'll be along shortly...

BTW...is it something we can help you with? Symptoms? Bike/year/model? Maybe we can provide some ideas so that when you do take it to the mechanic, you can make sure he heads down the right road...

[twowheelsprefered]

well, its only running on one cylinder. its a pristine 74' r90s i just had shipped up here from my brother. it fired right up and i put air in the tires gased her up and hit the road. tooted around town for a bit to get it warmed up then hit the highway. was running great i hit about 80 or so then it started just slowing down. i had the throttle all the way open but it was still slowing up. so i pulled off and it died. i checked the usual things petcocks, choke etc and all wa good. it fired back up and i limped home atabout 40. so heres what i found, both plugs are getting spark. both carbs are getting gas and when i rev it a little it back fires and slugs along. my brother had a real thurough service done 3 weeks ago, so i dont get it. if the plugs were not gapped right, or fouled or gas/ carb issues why did it run fine for the hour prior? and my brother rode it all over austin right up until he loaded it on the truck. so im stumped and i dont knoe enough to go tearing off into the electrical system

[97077]

Maybe that good mechanic is right in the mirror? I am so lucky to have a good friend and rider that took me under his wing. Mac has taught me so much about the Airheads. I'm not that mechanically inclined and I have made mistakes (luckily not costly ones) But just spending time and learning how to do some repairs is what makes Airheads a joy to own and ride. And Mac has some great biking stories that makes the time fun. What I'm saying is there anyone in your area that can help you? I have also learned a lot from other riders right here. Good luck. Kevin:brow

[20774]

Well, I've heard that most electrical problems are carb related!! If the problem is running on one cylinder, you can probably rule out timing. You could try swapping plugs, swapping spark plug wires, etc., to see if you can get the problem to move to the other side.

You could also have blown the diaphragm in the carb. It might have been OK but now with a big hole in it, it won't really let that side get enough gas. You could pull the air tubes off of each carb and then start the engine. You might want to put a box fan or something to blow on the engine. Let the bike warm a little bit. Then pull on the throttle and watch the slides in each carb. Do they rise together with higher RPM? If one goes up much more than the other, that would probably mean the diaphragm is holed.

Could be one of the floats has stopped working. If it sinks, that side will run rich and kill that cylinder. Or maybe you've got some crud that's in the carb. Drop the float bowl and see if there's any black or orange specs floating around. Black could be the fuel hose breaking down...orange could be the tank liner.

Could be your valves need readjusting. Usually that will be noticeable in that the bike won't idle very well.

Just some ideas...spark, gas, compression...it's got to be one of those...

Oh, and as just posted...check your MOA book for local Airheads....

[twowheelsprefered]

thanks alot. i'll get on that tomorrow. man, i hope i figure it out. i hate looking at nice things that dont work:scratch

[Boxerkuh]

I am with 20774. I would also check the coil. Take the tank off and see if everything is tight, check the carb cables... it might be something real simple. Will the bike restart? Run on one or both cyclinders? Put the cyclinder that is not running on TDC with the plug out and take a flashlight and look the top of the piston... Let us knwo what you find, give us bike info as well, we will be able to track it down. Are you an Airhead member? You can check for Tech days in your area and meet plenty of help. Good luck... :lurk

[twowheelsprefered]

ya i thought about it maybe being the coil. i took the tank off earlier and cleaned off all the connections. it will continue running when i pull the plug wire off of the non running cylinder, but when i pull it off the runnung side, it dies instantly. yas i am an airheads member. i didnt know they had tech gatherings like that. man, that would be great. i love working on my own ****, thats how you learn

[benway]

a 1974 R90S should have dellortos, so it wont have diaphragms

is the choke lever on? ie pushed down?

I would also check condition/free play etc in the choke cables, and the throttle

I believe a backfire in the muffler is usually a rich condition,

a pop in the carb, a lean one

hope that helps

[20774]

it will continue running when i pull the plug wire off of the non running cylinder, but when i pull it off the runnung side, it dies instantly.

Try to avoid doing this...pulling the cap off of a running cylinder. You create an unusual situation for the spark energy by not allowing a path to ground. The energy has no place to go and can damage the coil.

I forgot about the 'dells on the R90S...yep, no diaphragm. You might want to try a couple of drops of gas in the non-running cylinder and see if it will run. That could confirm an electrical problem. With the 'dells, you could swap them side to side, right? That could also be a way of isolating the problem.

How did you determine that you had spark? In keeping with the earlier comment, remove the plug and reinsert into the spark plug wire end. Lay the plug down on the fins so the threads touch. Then crank the engine...spark should be fat and blue, not weak and yellow. Plugs have been known to work OK out in the air but don't fire under compression. That's where swapping things side to side might help isolate the problem.

[20774]

While cruising another forum for /2 bikes, I ran across these recommended names/places in your area:

"I would call Nick Valentine in North Seattle. IIRC, you go west at
about the level of Northgate. Works from the basement of his house. He
has helped me with my post 1980 airheads; not sure if he knows the 1969
and earlier bikes but he could probably steer you. Good guy."

and

"You should also consider Kevin Brooks. He specializes in the old ones. He's
in Olympia and should be a short drive from Tacoma.

Here's his web site:

http://www.brooksmotorworks.com/"

[twowheelsprefered]

ive got bings on there not the dells. i got a nice blue spark yesterday, but i'll give it a try again

[twowheelsprefered]

hey thanks bro. ya, i know Nick. i called him 4 or 5 times yesterday. he's a pretty far from here and not that cheap either, but he is a good guy just the same. i havent heard of the other. i'll deffinatly look into contacting him

[benway]

if you've got bings then like Kurt said, check the diaphragms

[97077]

I had a problem with acceleration on my R80. The bike started fine and would run fine but as soon as gave it some throttle it would bog down. I took the carb a part and sure enough a big rip in the diaphragm. :brow

[ccolwell]

If it ran well before the service, then I would suspect something was done wrong. Check all the ignition electric connections to make sure a loose connection isn't killing the spark at higher rpm due to vibration. Check the air filter for obstructions, dirt or water. After that, check the coils and plug wires with an ohm meter. If you still have the stock plug wires, replace them with NGK pieces. Sounds more like an ignition issue than carbs to me. Unless the choke is stuck on, as suggested above.

[twowheelsprefered]

ya so i pulled apart the top of the carb, i dont see any holes at all in the diaphram. now im really stumped. ive swaped the plug wires, swaped the plugs, pulled the hoses that go to the airbox and lifted the slides on both carbs and they seem to drop at the same speed even when i cover that little hole up at the top of the openning. :dunno

[20774]

I ripped diaphragm could be obvious, but sometimes you have to kind of pull the rubber a bit to see if a hole opens up.

Swap coils? You don't necessarily have to physically swap them, but if you can make the left spark plug wire reach over to the right plug, etc., that effectively swaps them.

Have you tried some starting fluid into the throat of the carb (air tubes still off?) to see if that side will even run? If it doesn't, then you're really facing an electrical issue.

[twowheelsprefered]

yep, done both. nothing

[r60us]

Check the condenser.

[mrich12000]

Try to avoid doing this...pulling the cap off of a running cylinder. You create an unusual situation for the spark energy by not allowing a path to ground. The energy has no place to go and can damage the coil.

I forgot about the 'dells on the R90S...yep, no diaphragm. You might want to try a couple of drops of gas in the non-running cylinder and see if it will run. That could confirm an electrical problem. With the 'dells, you could swap them side to side, right? That could also be a way of isolating the problem.

How did you determine that you had spark? In keeping with the earlier comment, remove the plug and reinsert into the spark plug wire end. Lay the plug down on the fins so the threads touch. Then crank the engine...spark should be fat and blue, not weak and yellow. Plugs have been known to work OK out in the air but don't fire under compression. That's where swapping things side to side might help isolate the problem.

Avoid using raw fuel(gas),use a propane torch with the end removed, insert it intothe carb that is supect with the engine running turn on the propane, if the engine spaarks up on the cyle theat is out then it is aperent the carb is the problem..good luck.:ca :gerg :ca :bikes

[twowheelsprefered]

um, ya, where is that exactly?

[20774]

Check the condenser.

Wouldn't the condenser affect both cylinders? I thought the problem was one side runs the other doesn't...

[twowheelsprefered]

yes thats correct. its only the left side

[sgborgstrom]

I'm thinking bad sparkplug cap or torn diaphram.

How long did your brother let the bike sit before shipping it to you and how well did he store it? (if at all)

[twowheelsprefered]

he rode it the day prior to shipping. i looked at the diaphram, i dont see a hole

[ccolwell]

Block in the gas line below the T connector? That would be damned odd, but it's all I've got.

[twowheelsprefered]

the carb on the right is sucking air where the air hose connects, and the one on the left that is messed up, is blowing air out

[warredon]

Have you checked the valves cold yet to see if they are in spec? I would check their gap just to eliminate one more thing.

[20774]

the carb on the right is sucking air where the air hose connects, and the one on the left that is messed up, is blowing air out

Wow! The intake valve clearance must seriously be out of whack. The intake valve is opening when the piston is coming up to TDC.

[rocketman]

Wow! The intake valve clearance must seriously be out of whack. The intake valve is opening when the piston is coming up to TDC.

that's what I thought too, but for it to go that far out of wack that quickly you'd think there would have been some massive failure somewhere in the valve train and a hell of a lot of noise when it happened, esp since the bike was running fine just before it happened.

RM

[twowheelsprefered]

well thanks for all the input guys, but im tapped. its got me baffled. i guess its off to the shop we go! im sure it'll set me back at least 500 bucks.

[ccolwell]

If the carb is blowing instead of sucking (sorry, couldn't resist), and the valves are properly adjusted, and there isn't something horrilbly wrong with the valve train, then there must be a blockage in the exhaust -- maybe something crawled up there during shipping?

[20774]

Seems unlikely that something crawled up into the system...here was his second post:

"it fired right up and i put air in the tires gased her up and hit the road. tooted around town for a bit to get it warmed up then hit the highway. was running great i hit about 80 or so then it started just slowing down."

It was running fine and then abruptly began to bog down.

[beemerguru]

Are you SURE the points and timing hasn't changed? This still sounds a lot like the plate came loose and moved?!?

[20774]

In his second post, he says it's only running on one cylinder. I would think that the points plate slipping would affect both cylinders...

[ccolwell]

Seems unlikely that something crawled up into the system...here was his second post:

"it fired right up and i put air in the tires gased her up and hit the road. tooted around town for a bit to get it warmed up then hit the highway. was running great i hit about 80 or so then it started just slowing down."

It was running fine and then abruptly began to bog down.

I agree it seems unlikely, just going by process of elimination. It sounds like an ignition problem has been eliminated, and even if it were an ignition issue I don't see how that would cause the engine to blow air out of the carb. That leaves the intake/exhaust. The intake valve could be stuck open or so badly adjusted that it remains open. Or the exhaust valve could be stuck closed or so badly adjusted that it remains closed. Neither of those possibilities seems very likely.

If something got in the exhaust, then the bike might run well for a bit until the obstruction shifted and blocked it more thoroughly. Then it ought to limp at low speeds because of the crossover exhaust tube, but not run at high speeds. Again, unlikely but easy enough to check before sending it to the shop.

[20774]

I agree it seems unlikely, just going by process of elimination. It sounds like an ignition problem has been eliminated, and even if it were an ignition issue I don't see how that would cause the engine to blow air out of the carb. That leaves the intake/exhaust. The intake valve could be stuck open or so badly adjusted that it remains open. Or the exhaust valve could be stuck closed or so badly adjusted that it remains closed. Neither of those possibilities seems very likely.

You make a good point for taking off the valve covers, putting the bike in gear, and turning the rear wheel to see that the valves are operating correctly, rechecking clearances. Might be enlightening...

[rocketman]

Consider thou that if the intake was stuck open it would still suck air on the down stroke, as well as expel air on the upstroke. and such a sudden failure with out any noise, that is what really has me baffled. If a valve was stuck open then wouldn't there be a lot of noise as the rocker arm hit it and wouldn't the piston slam against it? It doesn't make any sense that something changed so suddenly, but obviously it happening so what is going on????

RM

[Boxerkuh]

I have been reading and re-reading... It sounds like what happened to my left exhaust valve in December.... the left exhaust valve seat was shot and the motor ate the left left exhaust valve, which was found in the exhaust system. That is why I said originally to look at the piston through the spark plug hole at TDC. Now my left spark plug was banged up and that was also an indication that something was wrong.
I would go back to the basics, maybe find a tech day close by, they are now all starting up, before taking the bike in to a shop to get a cashectomy done...
1. Do a complete valve adjustment to both sides, after the heads are torqued down.
2. Check the gap of the spark plugs, maybe install new one (depending on age and mileage)
3. Check the inside of the spark plug wire to ensure that the plug wires are good, maybe install new wires (depending on age and mileage)
4. Ensure that the plug wires are properly installed on the coil.
5. Check the carbs: the float level, what the bowl has in it, may need to clean it (depending on age and mileage), also make sure that the cables are working good.
6. Take the air cleaner element out and make sure that there is no obstruction
7. Test the fuel line just prior to the carb, to make sure that you have correct fuel flow, check both sides to be safe.

You are getting to know the bike and are eliminating one system at a time. Hope that helps some. :lurk :thumb

[twowheelsprefered]

what in the carb shoots the gas into the cylinder? im thinking its that simple. whatever that is, is clogged

[rocketman]

what in the carb shoots the gas into the cylinder? im thinking its that simple. whatever that is, is clogged

Its actually sucked in by the air moving over the mainjet that atomizes the fuel, the higher the slide and slide needle the greater the flow of air and greater amount of gas drawn into the chamber. So if its not sucking air then no gas flow. With the type of carbs you have the rate of rise of the slide is controlled by the vacuum formed above the diaphragm. So its much harder to flood an engine with those type since you need to increase the vacuum to raise the slide and that is tied to the rate the air is being sucked into the carb throat.

Are you sure about the lack of air being drawn in thru the carb? That still seems to be the biggest mystery, if in fact that is the case.

RM

[twowheelsprefered]

well, i pulled the exaust off and looked in there and the exaust valve is broken in half!! who woulda guessed. well i guess my next question is do i have to pull the whole head off to replace the valve? im guessing i do.

[twowheelsprefered]

any ideas what its going to cost me to have that head done?:banghead

[Bill Burke]

any ideas what its going to cost me to have that head done?:banghead
Rob-
Take it a step at a time. At least now you know what the problem is. Yes, you'll have to pull the head. What to do from here on out will depend on (1) the damage, if any, to the piston crown/cylinder) and (2) your pocketbook. Just having the broken valve replaced and the valve seats cleaned up will run you $300 or so. If you have some cash and like the bike, here's what I'd do at this point:
a. Find a knowledgeable airhead willing to help you pull BOTH heads;
b. Ship both (shipping UPS out of Staples, they'll box it up for you) heads to Ted Porter (he's the West Coast guru) http://www.beemershop.com/
c. Ted can examine both and will make his recommendations. A really good outcome (if you can afford it), is to have Ted do the headwork (new valves, new unleaded valve seats, new valve springs, new guides if needed). Now you're in the $500-650 range.

If the piston/cylinder suffered damage when the valve let go, then double to triple the highest number you see above.

If your damage is limited to one valve and you elect not to do both sides, you might get her back on the road for about $250.

This stuff happens. I lost an exhaust valve in Princeton, Ontario once, a thousand miles from home. I survived and you can too.

[beemerguru]

well, i pulled the exaust off and looked in there and the exaust valve is broken in half!! who woulda guessed. well i guess my next question is do i have to pull the whole head off to replace the valve? im guessing i do.


Depending on the budget, it might be wise to pull both heads. You most likely have a dent or two in the top of the cylinder..be great if you didn't but...

That could mean a new high compression piston...so might as well do it right for this bike.

Pull both heads, cylinders, pistons and rods. If you find a new piston, it won't be the same weight as the original so have the top end (pistons, rods, and wrist pins) balanced at a good speed shop. I've found as much as 4 grms difference in the sides.

Check the side of the cylinder to see if the broken valve gouged the surface..hope not. Clean and hone,,and a new set of piston rings.

Ted or Bob Grauer in San Jose for the heads. If one side went,,please check the other see how long it might have left.

I just finished a similar bike and the bill was a little over $600 for all the parts and work.

This is something you could do at an Airhead Tech day if you trailer the bike over. Learn how the parts come off and the order..

Or take it apart at home (special 12 point tool to take rod bolts off), send the parts off for fixing,,and use the tech day for assembly.

Not a difficult job at all if you have the right tools.

[twowheelsprefered]

thanks guys. i appriciate the info. its just been a few years since i was on an airhead, and im pretty exiteted about having bought this one. its ok though, i ve got other bikes, and a project truck. so, i guess thats why god gave two feet huh, one step at a time. :dance

[rocketman]

thanks guys. i appriciate the info. its just been a few years since i was on an airhead, and im pretty exiteted about having bought this one. its ok though, i ve got other bikes, and a project truck. so, i guess thats why god gave two feet huh, one step at a time. :dance

Well I'm glad you found the problem! Too it had to be what it was though, but yeah I'd say its worth the expense if you really enjoy airheads. I would think (hope!) its doubthful it will happen again. I still find it amazing that there was no sudden noise when it happened and am certainly glad that the valve didn't fall into the piston area, i guess the tight fit of it in the valve guide kept that from happening.

Look forward to your first ride report when its back on the road!

RM

[ducatipaso]

Maybe that good mechanic is right in the mirror?

the local law enforcement? :scratch

[12bswayed]

Rob,

If you decide not to do this yourself, Mick will take good care of you. He's done work on my R90S and other bikes I've had and has done a quality job each time. Last year, his rate was $72/hr., which isn't too bad, considering what the dealer would charge you and believe me, there isn't anybody at South Sound/Ride West BMW that will have the airhead knowledge like Mike does. It would be worth the drive...