pontigt05

got an 88 srv 540 single carb that just wont go.....idles fin but giving it throttle wont move on a load.....carb seems clear and all jets flow......plugs are wet, reeds look good and fuel pump is good....also compression is at 120.....cant figure this thing out...ne help would be appreciated

Rick

FxsX24

srv540.proboards80.com

the srv forum

pontigt05

Thank you!!

pontigt05

Went to Yamaha Dealer and talked with service guy. Told me to check fuel pump, reeds, carb, and see if crank seals were bad. Did all of the above which all ended up working fine! Im stuck on this one. Still remains to idle fine but wont rev at all. Just bogs. Anyone have any idea on what else? Compression is great, spark is great, one cylinder plug is a bit wet but helpo m eout if ya can. Thanks
Rick

IRONDOG

Probably your TORS switch screwing up on the carb- unhook the electrical connection on the carb and jumper across the connector on the wiring harness, not the carb harness.
Jerry
IRONDOG'S Snowmobile Swapmeet Free Ads

pontigt05

The TORS switch has already been done, so that cant be it....im leaning toward crank seals!! Ive seriously tried everything...Im out of ideas unless someone else has another idea? Fuel pump is good, compression is good, air box is clean, carb is clean, reeds are clean, and spark is good. Idles fine, just cant give it any throttle.

Rick

RPSS440

rideayamaha

did you try adjusting the top end on the carb, mine did the same thing, it wouldn't rev to over 2500 rpm, until i adjusted the scre on the carb. it's the one to the left ogf the idle adjustment, if your sitting on the sled. hope that helps

eric phazer

i would definatly check the jumper on the tors bypass, make sure its conected well.

i dont think its crank seals, if it starts and idles fine, crank seals will usually make it start like hell, and you would probably have to pump the gas just tokeep it running.

pontigt05

I actually pulled the cylinders off to inspect and found that one had been replaced with a used part that was 20 over. Now i dont know if they did the other one too and if they even changed the pistons to fit? I have to go have it measured tomorrow. This could be the problem having a stock cylinder and one that is 20 over. What do all of you think?

IRONDOG

Having one cylinder .020" over will not make a dime's worth of difference- it's done everyday with absolutely no problems. This is of course assuming it has been bored correctly. You said you had 120 pounds of compression. You said it idles fine, a bad seal would cause no or poor idle. I'm still leaning towards a TORS problem-it could be difficult to find, downstream from where you say you have it jumpered. You do have it jumpered on the harness side, don't you?
Jerry
IRONDOG'S Snowmobile Swapmeet Free Ads

pontigt05

Yes its jumped on the harness side.... Some one else told me to cross the cdi box wires and ground that, see if it runs...what do u think? I also heard that having one of the cylinders 20 0ver wasnt good? r u sure its fine? what does the thor cross do anywayz?

IRONDOG

Yes, I'm sure it's all right. All I do is powersports engine overhaul. I do all the boring, crankshafts, etc., for most all the dealers in the Flint, Michigan area. 020" over on one side is insignificant, no cooling problems, no balance problems, no problems at all. As far as the cdi box goes, there is one wire you can unhook and take all the switches out of the circuit, but I don't have a wiring diagram handy nor do I have an SRV here to look at. You don't jumper wires at the cdi box on an SRV to troubleshoot, someone has that confused with Arctic Cat's closed circuit CDI.
Jerry

pontigt05

Ok so what should i be looking for? should the two tors wires me wired together or??? I havent untaped it so i didnt look at how its done but i do know its not connected to the carb and looks to be wired at the harness.....That other cdi problem with the circuits, you think that could be it??? If you think so leeme know on that diagram or what I should try.....This machine is driving me nutssss.....I appreciate the help!!

rvanderklok

PLUGS ARE WET.....this means you're not getting proper burn. I'm willing to bet that there's a carb issue. Maybe the main has to be turned down, or maybe it needs a different jet. But if your plugs are wet then it's definately a fuel problem.
Where did you get the sled? Is it jetted for a different altitude?, Did it at one time have performance pipe, reeds, and clutching which the sled was jetted for, but maybe the performance parts were taken off before selling it to you?, Did you just buy the sled? Or did you have it running good last year?
I'm telling you..... something's outta whack with that carb!

Also, what's the temperature outside while you're running this thing??? Those SRV's run like a bag of crap when it's above freezing. What about your gas? is it last year's gas? Could you have gotten "bad gas" from the gas station???

__________________
Get on, sit down, shut up, and HANG ON!!!

spaz _head

Hello

I have a 85 SRV.

Here is your problem. SRV's are famous for having bad grounds. Attach a wire from the engine block to the frame.

It will fix your problem.
Let me know how you make out.

Later

mmrosshere

I am also an SRV owner. I would check the choke(enrichner) to be sure it is seated. that is not just an srv prob.

__________________
84 srv 540 starting to mod
98 indy classic xlt 600
LET ME OUT OF THE HOUSE

yamahaSRV

I have an 87 SRV 540 and I have the same problem, but I am almost 10% sure its the crank seals. Exhaust is coming out form them. I'm really not sure exactly where, but it pops and coghs when revving.

coolinthewoods

did you ever find a fix? could it be timing? or could you have a bad needle and seat in the carb?

kccats

That was my guess too float too high! What about a plugged exhaust? Or a mouse house in the air box or exh?