Xr650l feels gutless

[XRBrady]

Hey guys about a week and a half ago I purchased a 1997 Honda xr650l, on the test ride I could definitely tell the carb/tank had bad gas in it because it would sputter a bit, however the price was right so it came home with me one a trailer. First thing I did was drain the tanks and put some 93 octane gas in it, it perked right up but from what I've read I just expect it to be faster than it is. I'm about 6 foot 140-150 lbs and I read about how it wants to wheelie all the time but when i have to try for the wheel to lift in first gear.

The bike is de-smogged when I bought it and I just put a new spark plug in because the old one was toast. I fooled around with the tuning on the carb which helped some but I might be expecting too much. The bike still has a paper filter on it (not sure if that really makes that big of a difference) a fmf mega max slip-on on it. I had also looked into doing daves mods to the carb until I realized it's a mikuni, not a keihn or however it's spelled. Also the bike has been getting 33 give or take mpg on a tank which I feel is pretty bad, although I have been romping on it quite a bit. I appreciate it guys any help is better than none.

[EarthCruzn]

KEIHIN VE85CB – FITS 93-09 (and later) XR650L - 16100-MY6-772

 

I think someone has change your carb.............................. that would explain alot

Edited August 13, 2015 by EarthCruzn

[XRBrady]

So you're thinking that the changed carb is actually a downgrade from the stock?

[EarthCruzn]

It depends on the size / type of carb................... and how its jetted of course.

 

Many have change the carbs on these bikes, how yours is set up is really the question.

 

See if you can find the info / size of the carb ...........there are many here in TT that can assist you.............. as they may have done the same type of change...............

 

After you know what you have as far as the carb......... the next question is going to be how its jetted (size of jets) ect.............. what clip /  position the needle is in as well.

 

As far as the paper air filter goes the OEM is a "paper" type and a very good filter...........its just expensive.... and many use the "UNI" brand air filter as a aftermarket choice. (its cleanable) what ever you do do not use a K&N. (IMO) 

 

See what you can find out and post............... you have come to the right spot "TT" for help............ If you can post pic's of the carb as well.

[Muzz67]

Whats your gearing? If its very high geared, they dont feel very snappy.

  also needs too much throttle, killing the MPG..

[XR650L_Dave]

Where's the idle mixture screw on the carb- near the engine, or near the airbox?

 

near the airbox would indicate (not 100%) it's a 2-stroke carb, and that'd never run right...

[mcma111]

The XR650l in stock form is a SLUG.

[XRBrady]

Alrighty guys i've torn into it some so far the inside of the carb is completely disgusting, looks like there is algae in it. The idle screw is on the airbox side and that half-moon on the main jet i believe is making it seem to me that it's a 2-stroke carb. the numbers on it are t38-85a. I'm not entirely sure on where i'm looking to go at this point, a new carb is definitely in the future, but i may just try and clean it up and hope it runs somewhat better. Will get back when I dig further in and find jetting size in a little bit. i'll go take some pics for yall

[XRBrady]

[XRBrady]

Also to add, I don't know too much about carburators so sorry if my pictures are pretty worthless, it's mostly of the crap inside and outside to get a picture of what it looks like. My dad is helping me with the actual disassembly of the carb.

[EarthCruzn]

OK if you do decide to replace the carb.................... for a OEM

 

 

11 16100-MY6-772 CARBURETOR ASSY. (VE85C $200.19

 

http://www.servicehonda.com/

 

You have many other choices ......................even a different style of carb FCR ect...............

But for future refference this site has really good prices for OEM parts

[XRBrady]

Well I believe my throttle setup isn't stock either it's a single cable so I'll have to find something that will work with my setup. Thank you for your help!

[XRBrady]

So i tore apart the carb and there isn't a main air jet in it, in this thread this guy has the same carb and is asking why there was no main air jet.. https://www.thumpertalk.com/topic/815739-how-to-choose-main-pilot-air-jets/is there really just not supposed to be a main air jet in this carb?

[davidbogart]

That carb looks like the mikuni tm 38mm flatslide with an adapter.

[XRBrady]

It's definitely a 38mm however i think it was bored out like in the other thread I posted, I measured the I.d. Of the engine side and it was 40.7mm I believe

[garthr]

ive been running a mikuni tm40 pumper. it needed jetting cause it was way too lean. been running great for years without issues. find your info here by doing a search.

[XRBrady]

Alright so last night my dad and I cleaned everything up in the carb and moved the needle down a clip? It was first in the absolute richest setting so now we moved it down a hair to lean it out some. The jetting in it are as follows.

On the pilot jet I read what appeared to be Rh 7.5 but upon further research I am believing it is actually a 17.5.

On the main jet, the one on the bottom of the carb is a 250.

One thing I noticed when we had it apart is there is no main air jet in this carb. I have done some research and haven’t found out much on this but this is leading me to believe why its acting the way it is now.

After we got it all put back together, man the thing has really woken up. Only complaint is than now when there’s a bog around ½ throttle even when rolling on the throttle. But after the bog it feels like a turbo car coming under boost and it takes off. It’s actually kind of fun ha. My dad seems to believe that this is caused because there is no main air jet in it which can mess up the ?sensitivity? or something not too sure what that means.

Also above, under further research it is led to believe that these carbs are capable working with both 2-strokes and 4-strokes. However I can’t find any info on the main air jet.

Again all help is appreciated.

[Onederer]

The fuel economy is an indicator that the jetting is much too rich. If the jetting is too rich, it will have decreased power.

 

The paper air filter is the best at actually filtering. Many laboratory test have been conducted to determine the filtering ability of different filter medias, and paper is the best. For engine longevity, stay with a paper filter and just replace them when dirty. Unless the filter is filthy and needing changed, it's not the problem.

 

Thoroughly disassemble and clean the carburetor with cleaner and compressed before attempting to tune it. Make sure to remove all plastic and rubber parts possible before using carburetor cleaner on it. Using the straw the typically comes with a can of aerosol cleaner, make sure cleaner flows through all of the circuits. Replace the float needle and seat (if replaceable) if there is any grove or impression on the contact surfaces between them.

 

It's imperative that everything is in good working order before trying to correct a tuning issue.

 

A stock XR650L, with stock gearing, should have no problem doing a first gear, roll on wheelie, especially for someone of your weight. The bike really should feel quick with a rider of your weight.

 

The XR650L in stock form, makes very tractable power that is easy for new riders to control. The heavy flywheel weight and stock CV carb (your carb obviously isn't stock) make the bike much more difficult to stall and have a very linear power curve, which is great for recreational riding. In stock form, a XR650L is capable of speed in excess of 90mph, which is not slow, it just doesn't have the acceleration of some other dual purpose bikes or a modified XR650L.

 

It's a very reliable and long lasting dual purpose bike, and once you are able to sort out the problems, take it off road, where it really belongs.

[Onederer]

Also above, under further research it is led to believe that these carbs are capable working with both 2-strokes and 4-strokes. However I can’t find any info on the main air jet.

 

 

Two and four cycle engines are both internal combustion, reciprocating assembly, piston engines. A carburetor doesn't know which one it's bolted to, it just meters the amount of fuel delivered into the intake.

 

Properly sized and tuned, either engine will run on the same carburetor design. Four cycle engines have some characteristics that are easier to deal with by using a more specific carburetor, but overall, engines and carburetors can be used in many types of Frankensteinish ways. 

 

[EarthCruzn]

Here is a PDF of Mikuni carbs.............. look yours up and compare jets...............it will also tell you if it has an air jet ect............ diagrams are included

 

http://www.mikunipower.com/catalog/mikunicarburetorcatalog2012.pdf

 

More info and parts here if needed https://jetsrus.com/carburetor/a_carburetor_selection.htm

Edited August 14, 2015 by EarthCruzn