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  1. #1

    Slow starter, Cold Cranking RPM, Hard starting, and Low compression

    1. Could a slow starter cause low compression (yes). What should my starter motor be cranking the engine over at RPM wise? I watched a youtube vid last night and seems mine is a little slower than a few videos I found.

    2. Fuel pressure at crank is .5~.75 psi. Is this enough and normal? i figure not many folks have a fuel pressure gauge but I'm just hoping. I'm figuring this could either be a slow starter OR low compression (Or an air leak). My ski has hard cold starting - takes about 10~15 seconds while I manually prime it. Chokes reluctantly removed and carbs rebuilt. I also have not verified carb-check valve orientation - might by backwards?

    3. Low compression on mine - about 85psi across. 82 hours. Was 95psi at 52 hours but after I put a high compression head on the compression actually went DOWN to 85psi. The piston tops look great - perfect piston wash. No scoring or anything on the cyl walls. Crank-rod test seemed ok without taking things apart. Last time I comp tested it, I left the spark plugs and wires connected to 2 of the 3 on accident. Engine started, and compression gauge went to +/- 160psi in 3 seconds before I killed the motor (and then said OOOPPPs! my bad).

    2001 Modified GP1200R

  2. #2

    Join Date
    Jan 2006
    Texas City, Texas
    I'm still not buying the 85 compression. How can you have 85 compression, but when the engine is running it registers 160?

    Have you tried a different battery? Weak batteries could give the same symptom.

    Arrow should be pointing down toward the tank. The check is to help maintain a certain pressure in the tank. I thought the tank was supposed to maintain about 3-4 lbs, but do not know this for sure.

    Have you tuned with an aftermarket tachometer? I would have expected more than 6900 with that new head.

  3. #3
    elmatta's Avatar
    Join Date
    Sep 2011
    Buy yourself a new compression tester and borrow another working and in good condition tester. Fully charge your battery and make sure its holding at 12v. Redo your compression with 2 park plugs torqued into your engine 2-3 times each hole with each tester and give us those numbers. You'll then need a tachometer to record your idle and max rpm's. Fuel pressure should be 1-2 PSI for idle to 2000-2500. 4-5 psi at 6000-7500 PSI. If the tests fail with low numbers, you'll need to at least take your top end off and check the walls and rings again. Not sure how to check a starter for its cranking power. If possible, you could also take a look at your reeds for damage. If cylinders looks good, you'll need to take off the cylinders and look at the crank and connecting rod bearings/washers for damage. Make sure to take some pictures and post them here.

  4. #4
    Appreciate the response... I just put a new digital tach on tonight. Cranked for 10 seconds or so. No start tach said 820rpm cranking but it might be set to 2x. Engine didn't start. The weather sucks here and haven't had the opportunity to start it in 2weeks!!!

    The battery seems good. Hasn't run or charged in 2 weeks and it's never died on me. I put it on a tender every time I take the thing out which is like every two weeks. Needless to say it's got 12.5v in it.

    Don't get me wrong, if there's a problem then there's a problem. Its not stressing me out one bit. I like challenging rewards.

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