Thread: GP1200R Bog after carb rebuild
07-12-2010, 10:52 AM #1
GP1200R Bog after carb rebuild
I have a 2000 GP1200R which now has about 125 hours on it. Recently, my cat broke in the stinger, and my carbs were filthy. I removed the exhaust and replaced the cat with a d plate from Riva, and I removed and rebuilt/cleaned the 3 carbs. Also, I replaced the fuel filter, fuel selector switch, and spark plugs.
Upon putting everything back together, it ran AWESOME. I want to say it had around 117 hours when I did all of this work, so it's had around 8 hours on it since the work. Yesterday, I noticed that if I'm at anything below ~3000 rpm and yank on the throttle, it bogs like crazy. Sometimes it stalls out, and sometimes it works it way through it and picks up. If I'm above 3000 rpm, it doesn't do it at all. If it stalls after going WOT, that makes me think it is lean on the low end. If it just bogs and works its way through it that makes me think it is rich on the low end. Am I off here? Doesn't make sense why sometimes it stalls and sometimes it works through it though
So what I did yesterday was to be light on the throttle until the engine got to 3500 rpm or so then gunned it. Works fine like that, but I would like to figure out what is wrong. When I rebuilt the carbs, I did not mess with the needles. I didn't see a reason to possibly screw them up just to change an o ring that the rebuild kit provided. Also, I believe the accelerator pump is disabled - it kind of disabled itself. When I put everything back together on the carb rack, I noticed that the accel pump cam was not really touching the accel pump at all. I figured that since people disable it all the time, it is not a big deal.
Let me know if you guys need anymore information. Thanks for any help
07-12-2010, 02:41 PM #2
- Join Date
- Jun 2008
- St Clair Shores, MI
Did you re-jet?
It sounds lean to me. Rich would be if it popped and sounded like it was clearing out, then went. Whether it stalls or works its way through it, if it bogs or hesitates, without sounding like it's clearing it's throat, it's lean.
Not sure why this would pop up after 8 hours though. Check your fuel filter.
If you didn't re-jet, you should probably go a bit richer. These things are too lean from the factory. Especially in the mid-range.
07-12-2010, 04:55 PM #3
What did you set the popoff at?
07-12-2010, 06:03 PM #4
07-12-2010, 07:24 PM #5
You're not taking the hint - you likely have fuel problems. Hence, our comments about jetting and popoff pressure.
07-12-2010, 08:38 PM #6
07-13-2010, 01:25 PM #7
- Join Date
- Jun 2008
- St Clair Shores, MI
These skis come stock with carburetors, 2 stroke engines, and catalytic converters. That's your first clue that something is seriously compromised on these things right from the factory.
These skis are set up lean, especially in the mid range, to keep from killing the cat. I'm 99% sure that's what caused my first engine failure - a d-plate, stock carbs, and a 20 mile ride at mostly 3/4 throttle.
Do a bit of searching around and you'll find a lot of info on this site. I can see you're frustrated by some of the responses you get, but these guys get the same questions over and over again, primarily because the search function on this forum sucks giant donkey balls. You can probably get better results by going to google with your search terms and looking for the results from this forum.
There's a thread stickied around here somewhere - "jetting specs that I have used". Read it. Also, you should be able to find links to the service manuals and to the mikuni manual for these carbs on this site somewhere - probably stickied in one of the forums. The mikuni manual will tell you a lot about these carbs - read it.
If this popped up after hours of running beautiful, you probably have a clogged fuel filter, water in the fuel, or some other problem. But you should also jet the carbs a little fatter and check the pop-off (similar to setting float height in a normal carb, except much more of a pain in the ass). There are also high and low speed adjustments that are capped off from the factory - to access them you have to drill and remove some tamper resistant caps.
There are a lot of other tricks to messing with these carbs - i've spent hours reading these forums trying to figure out how to not melt down my motor. But the mikuni manual is a start.
There's also a page out there somewhere, I think maintained by a member here, that has some good step by step on tearing down these carbs and rejetting them. I can't remember how to find it right now, though.
07-13-2010, 04:21 PM #8
Just out of curiosity,did you adjust any of the low or high speed adjusters?i don't see the point of rebuilding a set of carbs without stripping them down completely.I found that when i rebuild mine,i made sure that the rubber o-rings on the new t-handle adjusters were tight and the adjusters didn't move,especially when the engine vibrates.(long shot but still a possibility).I would take them off,get pop offs checked (even if you start a thread and someone guides you through it),recheck your settings,and put them back on,make sure they are well sealed on as they do suffer from air leaks around the carb gaskets.Also take into consideration if you do rejet,you gonna need the filters and adapters.
07-13-2010, 05:49 PM #9
"Rebuilding" carbs does not mean changing some gaskets and calling it a day. It involves taking measurements, setting clearances, setting popoff pressure, making adjustments to the mixture on the highs and lows, etc. Do some searching/reading on the forum and you will get caught up with what all this means, and maybe it will help you with your current issue.
07-13-2010, 08:18 PM #10
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