# 98 Yamaha srx 700 trouble



## fishmagnetmike

My son has this sled run fine just quit has spark but won't start any ideas? What should we look for


----------



## fishmagnetmike

My son said he got it running it will idle but when you hit the throttle it backfires blows the pipes off and quits Any help would be nice. Thanks


----------



## NittanyDoug

Could be the TORS. Throttle override system. But that doesn't blow the pipes off in my experience.

The other thing could be carbs. Have they been cleaned recently? Did he possibly get bad gas? I'm sure he knows the srx likes premium fuel.


----------



## Burksee

My first guess would be a fouled plug, I've had them "fire" while checking for spark but wont fire well under compression. Bad gas would be another.

A great place to find help is the Totally Yamaha website.

http://www.totallyamaha.net/forums/forum.php


----------



## Crazy Axe

Plugged jet possibly bad gas would be the first place I'd look. I was playing with jetting on my sled because I read a lot of guys saying they are jetted pig rich from the factory and when I went a little lean, it hated it. Would move but backfire like crazy and popped the exhaust off once. Even blew the baffles out of the silencer.
If you wanna check something quick, shut the fuel off, pull all 3 plugs, one of you hold the throttle like halfway and the other turn the sled over, look to see if you still have spark. If not, could be the throttle safety switch.


----------



## swampbuck

They are factory detuned, all vehicles are. Back when I wrenched on sleds and boats, it was timing not carbeuration. Don't know if that's still the case.


----------



## Uncle Boopoo

If it runs/revs better with the choke on, the engine needs more fuel. AKA clogged jet(s), dirty carb port(s), fuel line blockage. If it's turning over but not firing, the plugs should be wet.


----------



## fishmagnetmike

Still trying to figure out this sled


----------



## swampbuck

Possible crank seal


----------



## NittanyDoug

If you can get it started spray some starting fluid or brake cleaner around the crank seal to see if idle picks up. If it does that's a sign of a bad crank seal.


----------



## gbflex

Clean the carbs, plugged idle jet will cause that.


----------



## grapeape

Most likely it is the TORS. I have rarely seen them go bad, 99.9% of the time it is an incorrect throttle cable setting at the carb that sets off the TORS. Easy way to check is to loosen the throttle cable and set the idle to correct rpm before re tightening the throttle cable. Another possibility is the update on the crank was not done or failed. If the crankshaft was updated, it will be stamped on the clutch side outside of the case seal I believe. Another way to check (maybe) is to have a Yamaha dealer run the vin number to show updates that were done.


----------



## fishmagnetmike

What is this crankshaft update


----------



## NittanyDoug

There were some years of the srx where there where crank issues. Yamaha welded the cranks as a fix/solution. But that's my memory.


----------



## countryboy17

Have you done a compression test on it yet?


----------



## fishmagnetmike

Compression is great


----------



## CHASINEYES

fishmagnetmike said:


> My son has this sled run fine just quit has spark but won't start any ideas? What should we look for


Maybe a pinched fuel line??

Very well could be a throttle safety switch, causing intermittent spark.

I don't get the backfiring blowing the pipe off. That's usually an indicator of fuel buildup in the exhaust, it detonates when you start it, BOOM. 

Spark and fuel usually means an engine will run...pull the plugs out and add 3 drops of fuel in each cylinder, put plugs back in then try starting it. Let us know what happens. 

Also, check the pulse line from crankcase to fuel pump, hopefully its clear. If it has a bow in the line, look for fuel buildup in the bow of the line, there shouldn't be a drop.


----------



## sjk984

Chu the carb sync linkage. If one became disconnect ed. That may allow fuel build up in the other cylinder s. Before detonation. 

Tors can be disconnected to chk for that.


----------



## fishmagnetmike

It will start and idle but when u touch the throttle it backfires out carb and blows off pipes


----------



## CHASINEYES

fishmagnetmike said:


> It will start and idle but when u touch the throttle it backfires out carb and blows off pipes


That's odd, unless there is either intermittent spark or that cylinder is somehow out of time. Is it hitting on all 3 while idling?

Does it always backfire from the same cylinder?


----------



## Uncle Boopoo

Possible timing issue causing the spark to be too retarded? That's assuming everything is 100% with the carbs. Including that they are synced properly.


----------



## sjk984

fishmagnetmike said:


> It will start and idle but when u touch the throttle it backfires out carb and blows off pipes


This sounds like a Tors issue. It does not engage unless the sled is throttled up


----------



## sjk984

Does the Tors light flash when the sled is first started. If it does not it is defective and will retard the dark so that the engine does not sustain damage


----------

