OK I am very frustrated at this point. decided to use my 1986 Reflex as a commuter bike for work (11 miles). Yes it is about as comfortable as a tack on a 2x4 set edgewise but 65 mpg is cool.

Problem is at high revs any gear under load and also no load, it spits, sputters and does kind of a backfire thing into carb. Really annoying at 50mph and in the dark when it stalls.

I have thought fuel issue, carb is CLEAN!!! (many times) tried various settings for air screw. Float adjusted so there should be enough fuel in there to drown an elephant, but not coming out the overflow pipe. Tank filter is clean and new inline filter. Jets are stock 38 - 92 but the main jet has "accidentally" been enlarged to 1.0mm

New O-rings on intake pipe both ends.

I also replaced cam chain and guides and rings. I initially thought the cam chain was the problem. Valves are a pain to adjust, that .002 of an inch is hard to get.

I have the shop manual, so it tells me how and what values to test the electrical things like rectifier and such, but I need to buy a new meter.

New plug NGK DR8ES "for extended high speed riding" before that was a DR8ES-L I thought maybe the old plug was too hot and cylinder was overheating.

I am going to try removing the baffle around the main jet. Stab in the dark as they say.

Thoughts, Opinions or just some witty remarks to help me out??

Edited August 27, 201213 yr by zippy

S_hit, give us a hard one next time. The pilot is too small, hard to find also. Adventure rider trials forum had a thread about cb400 jets. I `m inpatient. Drill it!! Also a larger CS sprocket can`t hurt. The air box needs all that silly stuff on top(the plasic looking pipes) removed they come right out and can be re-installed. The main could still be too small at your elevation. Seemed I had a 100 at 6000ft. If your main jet is as large as you say, try the air box first. Good luck!

Edited August 28, 201213 yr by lineaway

hi, your mains been drilled out to 1.00mm.....which equates to a 102.5 keihin main jet, so should be plenty. lineaway is right in saying the standard air box is restrictive. sure i read somewhere also that the ignition curve is not very good for top end running, and a cheepo pit bike cdi box helps. try the simple things first though.....

I alway like to say "Check yer grounds" on crap like this,ignition to engine,engine to frame,coil grounds,ect.

Not familar with Refluxes but if yours has a battery that could cause issues if it's bad. Does it have a resistor in the plug cap? Seems like I remember those causing problems in old hondas.

P.S.My buddy Bill just bought one of those new Honda dualsport 250s,getting 80mpg right outa the crate...Looks cool,runs smooth(Fuel Injected),pleasant to ride,shifts perfectly,and dirt cheap!!!!under 5k out the door...Bill has a couple of Reflex he could be street riding too,prefers a little comfort instead

Edited August 28, 201213 yr by htrdoug

S_hit, give us a hard one next time. The pilot is too small, hard to find also. Adventure rider trials forum had a thread about cb400 jets. I `m inpatient. Drill it!! Also a larger CS sprocket can`t hurt. The air box needs all that silly stuff on top(the plasic looking pipes) removed they come right out and can be re-installed. The main could still be too small at your elevation. Seemed I had a 100 at 6000ft. If your main jet is as large as you say, try the air box first. Good luck!

Would the pilot have anything to do with high revs? It idles and performs well at low RPM.

What size bit should I drill it with?

I went from a 10 tooth CS sprocket to a stock 13 tooth.

will try the airbox opening up idea.

hi, your mains been drilled out to 1.00mm.....which equates to a 102.5 keihin main jet, so should be plenty. lineaway is right in saying the standard air box is restrictive. sure i read somewhere also that the ignition curve is not very good for top end running, and a cheepo pit bike cdi box helps. try the simple things first though.....

any idea what cdi box to look for? If I need to go that route.

I alway like to say "Check yer grounds" on crap like this,ignition to engine,engine to frame,coil grounds,ect.

Not familar with Refluxes but if yours has a battery that could cause issues if it's bad. Does it have a resistor in the plug cap? Seems like I remember those causing problems in old hondas.

P.S.My buddy Bill just bought one of those new Honda dualsport 250s,getting 80mpg right outa the crate...Looks cool,runs smooth(Fuel Injected),pleasant to ride,shifts perfectly,and dirt cheap!!!!under 5k out the door...Bill has a couple of Reflex he could be street riding too,prefers a little comfort instead

Battery is new this season.

no resister in plug cap that I know of. ( I also took cap off and trimmed wire and redid connection, same result in running)

I may need to go over the grounds again.

I am too cheap to spend around 5k, already got the Reflex.

Thank you for the replies, anybody got more ideas I welcome them.

Wish me luck............Or I get out the BFH

Thank you for the replies, anybody got more ideas I welcome them.

Wish me luck............Or I get out the BFH

Yea, sell you my XT 225 Serow for 2K, come get it!

I know you probably have but double check your timing , to much advance can do what you describe too. It is a pain to do but you can check one with a light at upper rpms . May take 2 people to get a accurate view thru the little timing mark hole ....

Have fun nonetheless...!

Yea, sell you my XT 225 Serow for 2K, come get it!

You have said that Serow is a fun machine to ride. But unfortunately it would cost me about $2000 in fuel just to pick it up. A hard sell to the little woman. Now if I could somehow get some riding done and a family vacation out of it........Nope still won't go over well.

I know you probably have but double check your timing , to much advance can do what you describe too. It is a pain to do but you can check one with a light at upper rpms . May take 2 people to get a accurate view thru the little timing mark hole ....

Have fun nonetheless...!

Actually no I have not checked the ignition timing. this thing is not adjustable. But checking the timing would help diagnose if I need a new CDI for it. HMMMM may have to check into this. Book says I need to hook up a tach along with the timing light. any way of being relatively accurate without the tach?

OK removing the baffle around the main jet did not do anything. I didn't really think it would.

I have removed the tube looking structure from the airbox. next will be a test ride.

This may take a few days to get this sorted as I have decided to try one thing at a time.

Edited August 28, 201213 yr by zippy

Would the pilot have anything to do with high revs? It idles and performs well at low RPM.

What size bit should I drill it with?

I went from a 10 tooth CS sprocket to a stock 13 tooth.

will try the airbox opening up idea.

I do not remember what I drilled mine . I think the result was around a 45 or 48. The idea was stock was lean. Everyone always forgets the pilot always flows! Mine coughed and sputterd at mid revs and this fixed it. Good luck!

The Reflex does not use the battery for the ignition system so you do not need to look there.

Lineaway, thanks maybe some googling and I will find what size hole Keihin 45 and 48 jets have in them. While at work I was thinking about that pilot and was beginning to think that the main supplements the fuel to what the pilot provides. So I was thinking they work in conjunction of one another.

mcman56, yep I had the bike stripped of lights and used it as a trials bike for setting up sections for Beginner and Novice classes. Never really revved it up, so did not notice this problem at the time.