Piston and Cylinder scoring on my LTD :(

[shizznats]

Alright... so we finally got nice weather and were ready to figure out if our engine was going to start/run with 90psi compression. We hooked everything up, and disappointingly, after hitting the starter a few times, the starter turned the engine over, but it wouldn't fire at all. My buddy grabbed a can of carb cleaner, sprayed into the carbs, and after that, the engine immediately started up and the revs increased rapidly (idle speed screw was turned in 1.5 turns like the manual states). I had to back off the idle speed screw a good 3/4 turn to get it to idle around 2500rpm. We shut if off shortly after and when trying to start it again after about 5 minutes, it again wouldn't start. Again, a spray of carb cleaner got it to start right up. Choke didn't seem to have any effect one way or the other. I'll also mention it's about 65 degrees when we were doing this if that makes any difference.

Once we had the motor running for a while, we noticed something else. When restarting the motor shortly after it had been shut off, it would start up, idle low and rough and then die. I had to turn the idle speed screw back up that 3/4 turn, start it, and after a second, the revs would start climbing so I would back it off that 3/4 turn and have it idling at 2500 again after which it seemed to run ok.

Just trying to figure out what these might be symptoms of. We are running on 35:1 premix. The motor seems to run fine (though we haven't had a load on the engine yet as the clutch is off) but has trouble starting. Any ideas? Thanks!

[Interceptor398]

If you are running 35-1 oil plus the oil injection it might be to much??  It should smoke a lot.  Do you know the condition of the fuel pump?

[shizznats]

Yes, it smokes like crazy. We bled the air in the oil lines so the oil injection is working full time now as well. Fuel pump is brand new. How much of a difference does it make that we don't have the clutch on as far as the idle speed screw is concerned?

[jimvw57]

you don't think someone maybe opened up the cylinders a bit, might be keeping the rings from sealing all the way, or maybe cylinders are out of round?? never had a motor I rebuilt down around 90 psi after assembly.

90 PSI will be hard to start.

[shizznats]

Ok, understood. But will 90psi seemingly run ok without a load on it once it's started? Or would it run rough? Like I said, it starts right up with a little spray of carb cleaner. I am going to get a good compression gauge now because I don't know if I trust the readings off this old one.

[shizznats]

Just got home with the new compression tester and the results are gooood. 130psi in both cylinders =)

So this means our starting problems are not a result of low compression but rather something else... probably carb related. Any other ideas out there for why an LTD motor would not want to fire unless carb cleaner or something similar is used, but runs perfectly fine once it's started? Also, the idle speed screw needs to be turned in more to get it started, but then has to be backed out because the engine revs climb to around 4000rpm. Thanks!

[Joel]

What carbs do you have on it? Did they get soaked in carb cleaner and all passages opened? Joel

[Checkmarks]

90psi, 130psi, why do I bother? 

Replace the main jets, power jets, pilot jets and the rubber o-ring in the carburetor.  Verify the pilot passage is clear.  Balance the carburetors.

If there is still trouble fix the fuel pump.  A new fuel filter (big automobile type), open the fuel pump and rebuild or inspect for serviceability and replace the impulse line.

[shizznats]

90psi, 130psi, why do I bother? 

Replace the main jets, power jets, pilot jets and the rubber o-ring in the carburetor.  Verify the pilot passage is clear.  Balance the carburetors.

If there is still trouble fix the fuel pump.  A new fuel filter (big automobile type), open the fuel pump and rebuild or inspect for serviceability and replace the impulse line.

Haha I just looked back and you really nailed those numbers, lol. Where is the best place to get replacement jets for these carbs? I have the Keihin BD40-36's on this motor. Thanks!

[gixxer6]

Are you sure your compression tester is accurate?

Alot of guys pull the Keihns off and put on a set of Mikuni's.  Parts for the Keihins can be hard to come by...

[Joel]

The accelerator pump diaphrams are still available,however the bowl gaskets (orings) are difficult to find or not at all,but if you can keep it in tact and use anerobic gasket maker (Permatex) with the old gasket it works great. Jets can still be had as well. Joel

[kawhead]

i would say hard starting could be caused by the keihins,kinda touchy, [what idle screw do you speak of, speed or mixture?]also, put the clutch on, it also acts like a flywheel,adds to rotating mass at idle.

[Checkmarks]

Dump the Keihins and flush up some 36mm or 38mm Mikuni's.  Likely all carburetors are good and good enough for the Kawasaki manufacturers of the sleds to call them OEM.  This only applies when they are new and then only warranted for the year.  Thirty years go by and guess who is my number one choice for even used old carburetors. 

Claim away but do not ask me to help you start or tune your sled if you have other than Mikuni.  My poor friends, belly up and admit what so many learn.

Follow through with purchasing 38mm and those specifications I can share.  Better search the forum and find your answers. 

[kawhead]

on my 82 ltd i used a set of 440 invader carbs and started rich,[many junked invaders]ended up at stock jetting,runs very nice,trucker even mentioned how well it started.[no e start]

[gixxer6]

I have an extra set of 440 Invader carbs if you're interested, PM me.