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  1. #1
    silver93t's Avatar
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    GP1200R part throttle hesitation

    I just got my 2000 GP1200R together and on the water. Long story short, the previous owner left a hose loose and the ski flooded. The carbs were sized as well as the starter. Not knowing the problem, he pulled the motor with plans to rebuild it but never finished it. I went over everything and put the ski together. The motor 59 hours on it and 120-120-115 compression front to rear with no apparent leaks. I picked up a set of low hour carbs, rebuilt them with genuine mikuni parts. II also installed t handle adjusters, drilled out the return restrictors, and added a 95 jet as a restrictor per OsideBill's write up. I re-used the original jets. The catalytic converter was repaced with a Jetworks plate and chip. All the gaskets were replaced on the intake and exhaust.

    I started with all the low speed adjusters 1 turn out and the highs 1 and 1/2 turns out. The rear carb I opened a bit more as I heard the rear cylinder tends to run lean. Idle is smooth and set at around 1100 rpm in the water. When giving it throttle, there was a bad hesitation. I immediately pulled the plugs and verified it was a bit lean by the grayish color on the electrode. I then opened up each high speed adjuster 1/4 turn at a time and would do a few short blasts. Each time the hesitation became less apparent. I reached a point where the ski started to bog worse at about 1/2 throttle and wouldn't accelerate through it, so I assumed I went too rich. Backing each high speed adjuster 1/4 turn seemed to aleviate this.

    I put about 3 hours on it today riding with a couple of the guys on here. It feels good everywhere except at about 1/2 throttle where there is a slight hesitation. I can avoid it by feathering the throttle. If I give it throttle too fast it will bog but eventually accelerate through it. 3/4 to full throttle feel great. I pulled the plugs after today's ride and they are all an even black color aorund the electrode. I can post pics tomorrow. My question is what do I adjust from here to eliminate the hesitation I am experiencing?


  2. #2
    caliburn's Avatar
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    I have the same issue with bogging, went through and put a D,plate and block off kit for mix and now at 4000 rpms it bogs, if I push it she will die and if I feather it I can get it through it and after that it runs fine from that point on, so I to need to figure this out on my 01 GP1200R, is yours Premix?

  3. #3
    silver93t's Avatar
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    Mine is premixed. I would say mine does it around 4000 rpm too. I did put in 93 octane because I had some old gas left in the tank. I may try 89 or 87 octane next time I fill up.

  4. #4
    silver93t's Avatar
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    Plugs front to rear starting from the bottom. Yes I know about the top of plug 3 it got stuck in the wire. Front cylinder looks leaner to me so I opened the high speed adjuster an additional 1/4 turn.
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  5. #5

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    Removing the CAT creates less restriction and more airflow through the engine. You need to re-jet. Check out OsideBill's jetting recommendations.

  6. #6
    silver93t's Avatar
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    Im re-jetted per Oside Bill's recommendations. I found the issue a while back. It was a late night when I did the carbs and I somehow put a restrictor before the last carb instead of after it. The ski is winterized right now but once it warms up Ill fix it.

  7. #7
    No need to rejet the carbs after installing dplate

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