no effect from 2 cylinders

[superman]

I have a Suzuki DT115 starts and runs, good compression on all 4 cylinders and it is firing on all 4 cylinders. If you remove 2 & 3 cylinder wires it will start and run and has no effect. If you remove i & 4 it won't start even if you prime it. Any help appreciated. Thanks

 

[JB]

Re: no effect from 2 cylinders

Hi, Superman.<br /><br />I think your engine is lying to you. 2 strokes will sound just fine runnning on 2 cylinders.<br /><br />What happens if you pull 1&4 while the engine is running? It will probably die.<br /><br />I think you have an ignition problem. 1&4 share a circuit on most V4s, and 2&3 share the other.<br /><br />Good luck.

 

[superman]

Re: no effect from 2 cylinders

Hi JB: If you pull 1 & 4 it dies. Also if you check for spark it fires on all cylinders. Any Help appreciated

 

[JB]

Re: no effect from 2 cylinders

Hi, Superman.<br /><br />Hmmm. It may be a difference in how we number the cylinders. Are you numbering 2&3 as one side (bank) or both bottom?<br /><br />Is there a chance that you have 2&3 plug wires switched?<br /><br />Put some premix in a spray bottle and spray into each carb throat, with special attention to the throats that feed 2&3. If it picks up rpm you probably have a fuel starvation problem on those two.<br /><br />To make power, a cylinder needs:<br />Spark. You have that.<br />Fuel/air. Suspect. Could be carb or reeds.<br />Compression. You have that.<br />Timing. Possible suspect.<br /><br />Good luck.

 

[superman]

Re: no effect from 2 cylinders

Hi JB: What I'm calling 2 & 3 cylinders is the t middle cylinders. It is an inline 4 cylinder with plug wires numbered on the coils. they are all four mounted by the cylinder they fire. I can take the plug out and the plug is slightly wet. I can put rhe plug back in and I can put the wire on a spare plug and ground it to the engine block and it fires.

 

[JB]

Re: no effect from 2 cylinders

Hi, Superman.<br /><br />Did you try the fuel spray to the carbs/throats that feed 2&3?

 

[superman]

Re: no effect from 2 cylinders

Yep I tried that and no effect

 

[JB]

Re: no effect from 2 cylinders

Well, Superman, I'm sorry to say I have used up generic troubleshooting techniques. <br /><br />It's time for someone familiar with your engine to help out.<br /><br />Good luck.

 

[Hooty]

Re: no effect from 2 cylinders

Compare plugs 2 & 3 too plugs 1 & 4 after running. Any difference?<br /><br />c/6<br /><br />Hooty

 

[superman]

Re: no effect from 2 cylinders

Hi Hooty: If there is any difference the ones on 1&4 maybe slighty wetter. I tried putting a little fuel on the plugs on 2 & 3 but no effect. When you remove 2&3 plugs when the engine is hot there is a little smoke comes from the cylinder but I don't know if this evaporation or smoke residue. any help appreciated. Thanks

 

[Hooty]

Re: no effect from 2 cylinders

Get yourself one of those spark testers (NAPA maybe) and see if 2 & 3 will fire across that 7/16" gap (check manual for gap spec.). Plugs can fire out in the atmosphere but if the spark is weak it won't fire under load (Compression). I don't think those testers are very expensive and it should be adjustable.<br /><br />c/6<br /><br />Hooty

 

[superman]

Re: no effect from 2 cylinders

Thanks Hooty, I'll get one and get back to you.

 

[BigFellaQld]

Re: no effect from 2 cylinders

Suzuki 115 and 140 shared this problem, and its not a simple fix, although fairly common. The crankshaft has sealing rings, which keep the crankcase area of each cylinder seperated from each other. This is necessary on any 2 stroke, as they need to compress the fuel/air mix in the crankcase, which forces the mix through the ports, and into the cylinders, as the ports are uncovered by the downwards travel of the piston. Occasionally, usually as the result of a backfire, the seals will fail, allowing crankcase compression to "cross-over", between cylinder 2 and 3, making it impossible for the engine to use those cylinders, due to no incoming fuel/air charge. The only way to fix the problem is to rebuild the motor, and reco the crankshaft. Suzukis were always more susceptible than others, due to them using actual lipped seals, where most other manufacturers use rings or labyrinth type seals<br />Regards, Paul

 

[superman]

Re: no effect from 2 cylinders

Hi BigFellaQld: I hate to hear bad news but I am glad to find the problem. About how much do the parts cost to repair this?

 

[superman]

Re: no effect from 2 cylinders

How big of a repair problem is this and how much do the parts cost to repair.

 

[Hooty]

Re: no effect from 2 cylinders

I read BigFella's reply and I'm trying to figure how to test for ringseal leakage between cylinders. I may start another topic to find out.<br /><br />c/6<br /><br />Hooty

 

[superman]

Re: no effect from 2 cylinders

Good, All help is appreciated

 

[Hooty]

Re: no effect from 2 cylinders

What's the firing order for that Suzuki?<br /><br />c/6<br /><br />Hooty

 

[Hooty]

Re: no effect from 2 cylinders

That's not what I wanted to know. Is that a in-line or V4?<br /><br />c/6<br /><br />Hooty

 

[superman]

Re: no effect from 2 cylinders

It is an in-line 4. The 2 center cylinders are the problem