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2005 trx450r low engine speed bog

3K views 5 replies 2 participants last post by  duke416ex 
#1 ·
Hello all, finally decided to get on the forums since I've had so many questions answered before!

Here is my specs, I have a 2005 450r with Hrc cam, hrc lid, moose foam filter, hrc jet kit 185 Main 48 pilot, needle 3rd position. The guy i bought it from earlier had a full White bros pipe that he took off for some reason before I bought it ( I know sounds shady) but he put the stock pipe back on with the hrc tip, which I was running with out the baffle it because it made an awful vibration sound at high rpm like a loose skid plate. I'm in the process of getting a slip on so it will be done right.

Ok so here's my problem. The quad was running awesome when the first week I had it, besides a few decel pops I'm guessing that were amplified from no baffle, it ran good, no bogs at all except it would very rarely die when letting the clutch out in second which I heard could be normal for these high strung motors. It all came to crap when at a friends house I decided to race him and I was idling for about 3 mins, the idle was a bit high and my friend ran over pointing at my orange exhaust by the head pipe, being that this is my first truly high peformance sport quad I thought that it was the end of the world, only to find out that it's normal lol only at night at least and it was pitch black out, anyway i suspected it was running lean so I screwed with the fuel screw and cleaned out just the pilot, the main and the bowl, the rest looked very clean. When I put it back on the quad would not start at all! Literally 100 kicks and not even an attempt, I had to resort to giving throttle while kicking (I know this is really bad) and it fired right up, revved fine, smooth and quick. Taking off in first it felt like the idle was too low kinda like chugging along and then it takes off. The bog occurs at lower rpms I'm gonna guess maybe 3-4K ( very rough estimate) it doesn't die but sounds like a fuel cut and then once it gets out of that dead zone it runs like a top and accerlartes all the way to the rev limiter without any hesitation. I noticed it does it worse when going uphill and at a lower rpm, when going downhill it's barely noticeable but it's there. If I try to do a first gear wheelie after just taking off it also does it. Seems like it cuts out under load but only at lower engine speeds and doesn't make the quad stall just temporarily stutters.

I'm guessing it's maybe something to do with the stock pipe? But I wanted to hear from more educated people on this site

Forgot to add I tunrned the fuel screw all the way in and turned it out 2.5 turns. Does that sound about right? Thanks guys any help is appreciated
 
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#2 ·
2.5 turns out is a good start. That jetting is a good starting point for a 450 with your mods and a full exhaust. Having the stock exhaust even with the baffle removed will change the jetting some. If you are having to pump the throttle a little to start chances are you need to be a little richer on the pilot. I would probably start out checking the hot start and make sure it isn't stuck open as that will cause a lean condition before I changed jetting though. jmo
 
#4 ·
take the seat off and you will see a cable run to the middle of the top front of the carb. That is where the plunger goes into the carb. It simply unscrews. Be careful with the plastic nut as it will strip easy and also when tightening can break too. Sometimes the plunger gets stuck open or the spring will break and not push it back in a it should.
 
#5 ·
Ok thanks for the fast reply, I'll surely check that out.

Do you think I should go up 1 with the pilot? And would a slip on be sufficient or does it have to be full? Also I forgot to mention it has the Hrc headpipe also.

Thanks again.
 
#6 ·
You could try up one on the pilot and see how it acts. If you have to go out 3 turns or more on the screw you need a bigger pilot.


If it has an hrc head pipe it is off an 06 as they didn't make a head pipe for the 04-05. You may need that info when getting the slip on. It just depends a lot on the slip on whether it might work or not. You would probably be better off finding a complete full exhaust. You can find some good used ones cheap here at times and even with a repacking they are still a lot cheaper than new.
 
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