Thread: GPR won't rev above 3k
07-01-2012, 06:42 PM #1
GPR won't rev above 3k
I have a 2002 GP1200R that will only rev to about 3000 rpms then bogs down. Most of the bogging issues I've read on here are carb related. I am sure that's not the issue because Oside Bill just rebuilt them. I have a new reman motor in it with no hours on it. It ran great on the hose yesterday and I put it in the water today. It took off and ran great for about 2 minutes then it wouldn't rev past 3k. It still idles fine and everything seems good untill it hits 3k. It has a new fuel filter and everything is stock. I have 32:1 premix in it (Amsoil Intercepor). I have BR8ES-11 plugs in it and they look good. The compression is good 117-118 on all 3 cylinders. When I first put this engine in it had a terrible backfire and after some checking around the only thing I could figure that caused it was the carbs. It wouldn't rev above 3k then either. So it seems I still have the same issue but with no backfire. I am wondering if an air leak around the intake gaskets would cause a bog like this? I used the gaskets SBT sent with the engine. I didn't think they looked that great but it was all I had so I used them anyway. Bill sent a really good looking gasket with my carbs and is sending anither one so maybe I'll try those. I'm stumped, any ideas?
07-01-2012, 09:25 PM #2
cat converter still in it? Possibly broken? Or maybe a powervalve issue...
07-01-2012, 10:01 PM #3
The cat has been taken out, I forgot to mention that. I also made the exhaust free flow. I did that because the sound box exploded when it backfired. I loved the way it sounded today when it did run good for a couple of minutes but I think it could get annoying so I might switch it back. The powervalves seem to be working good. They cycle open then closed when I shut the engine off. There shouldn't anything wrong with them internaly being on a fresh engine.
07-01-2012, 10:37 PM #4
If it backfired you could have reed problems. Don't know anymore than that
07-02-2012, 08:04 AM #5
- Join Date
- Nov 2009
Did you pressure test motor before you dropped it in?
I would no matter who rebuilt it.
07-02-2012, 08:55 AM #6
No, I did not pressure test it. SBT claims they test all their motors. I know what you mean though, I wish I would have tested it now. If something was plugged in the pick up unit in the tank would that allow it to run at an idle and low rpms but bog down at higher rpms? Or would it cut out no matter the rpms? I checked the reeds after the backfire and they were good.
07-02-2012, 09:15 AM #7
This. Lean backfire. The motor could be sealed and you could be getting air in from your exhaust manifold, carb rack....etc.
07-02-2012, 09:21 AM #8
Is there a strong vibration? Maybe you sucked a rope or something in the intake grate? When it gets wrapped around in there it will do this as well.
07-02-2012, 10:06 AM #9
Just checked the pump and there is nothing stuck in it. I started it again and got a small backfire. I sure its sucking air somewhere. I'm going to put new gaskets on the carbs and see what that does.
07-02-2012, 06:08 PM #10
I am wondering if this could be something electrical. If the pickup coil was bad would that mess with the fireing order and make it run rough and not rev up past a certain point? I've got good spark but if it wasn't fireing every revolution would that make it run rough and backfire sometimes?
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