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Discussion Starter · #1 ·
Hey guys..


1) I'm gonna up the jets this weekend. I've done some research on here but just making sure.

Got a DG slip-on (yeah..i know..)
UNI filter with an unhacked box

From what i read i need an 42-45 pilot, 150-152 main?

In PA the temp fluxs from anywhere to 0 degrees to 110 degrees

2) Any easy way to grease all bushings? Can i tap some grease fittings in the A-arms, steering stem, etc?

3) Best oil to use? For now been using Honda GN4 oil. Any better?
 

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Pro Honda HP4 4-Stroke Motor Oil, (this is the gold bottle red cap at you local dealership, its not as thick). As for the jetting unless you are experiencing lag in throttle response or in the low end, leave the pilot.. I left my pilot alone, and my 400 runs great. Because I live in cali I have a 168 main in mine, but that is due to the elevation I ride at. Just try different jets until it feels good all the way through the gears, actually ride the bike and run through the gears. Pull it into the garage, and pull the plug. If it is clean you are to lean you need to go up, If it is black you are too rich and you need to go down a jet. Because they run in 2's if you had say a 168 you would have to go down to a 166. like your 150 and 152. Easiest way to do this is go to a bike shop pick up a jet kit, and that way any mods you make in the future you have the jets to compliment the mod.. Good luck bro. Hope that helps a bit.
 

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Play with the jets - find out by experience. Everybody thinks more fuel = more power. Wrong - lean is mean. Run it as lean as possible without burning it up and it will be fast.

Best oil? Whatever is readily available in in your area. Just make sure it is API rated SJ or lower or anything with the JASO rating. I use Silkolene synthetic 15W50. Cost about $20 a quart. The GN4 is petroleum oil (about $6.50 here) and the HP4 (about $8.50) is semi-synthetic. They are all acceptable. It just depends on how you care for the motor.
 

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Discussion Starter · #4 · (Edited)
Thanks guys. I will experiment with them. Right now its at stock jetting levels. It bogs in the low end, takes forever to stay running when cold, and backfires like a mother when decel'ing. But it does rip mid-top when warm. A/F screw is 2 3/4 out. Sounds like they both need sweetened up.

Due to this bike being 12 years old maybe just stay with GN4 because i have heard switching to synthetic in an older engine is bad for seals and bearings?

And can i drill in some grease fittings for better lubrication? Or would they cause more outflow?

Thanks guys
 

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Now we have some information to work with.

If you are bogging on the low end; it is probably a fault with the accelerator pump. The accelerator pump is supposed to squirt a shot of gas into the throat of the carb as it is opened to get past the lean condition caused by the vaccuum drop when the slide and/or butterfly opens. You need to remove the carb and inspect the pump diaphragm. If the diaphragm is good, check the linkage that operates it. The pump should start to pump as soon as the slide moves.

The backfiring might be caused by a defective air cut valve on the side of the carb. The air cut valve is supposed to cut the air to the idle circuit during deceleration to prevent backfiring in the exhaust. If th air cut valve has ruptured, it will not operate as designed and it will allow extra air into the idle circuit making it idle poorly and extending the warm up time.

I would recommend that you look at other things before trying changing jets.

Just like other myths, changing from petroleum to synthetic oil is no more like to cause seal damage than changing from Honda oil to a different brand. If you change and the seals start leaking, it's because the seals were about to start leaking anyway.

Last, you can put in grease fittings in the A-arm pivots, but it is likely that when grease is pumped in that it will push the seals out. I do not recommend doing it.

Happy motoring
 

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Discussion Starter · #6 ·
Here's a video of one of the first fire-ups after the stock cam install, crf450 chain, adjusted valves and cleaned carb.

Might help point out the jetting issue. The temp was about 40 degrees that day.

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