So I've have narrowed my problems down to my carburator. I have it running pretty decent. The only thing left is whenever the throttle is advanced it seems to cut out or bog.
Anyone have any idea what would cause this?
Second, Could anyone that is running a Mikuni hsr45 Tell me what needle and jet you are using so I can have an idea about where I am.
Any help would be appreciated.
Thanks,
Dave Brendorfer

 

We need to know your normal riding conditions, ie. elevation, temp, etc.
Do you have the accelerator pump activated? What kind of air flow with the intake and exhaust???

 

Here is some info from Hightower...

General Mikuni TM45 info for the DS650.

The TM45 is a direct pull flat slide carb with an accelerator pump, rather than a vacuum slide carb like stock. When you hit the throttle on the TM45, the slide opens immediately allowing instant airflow. An accelerator pump is used to squirt fuel into the carb throat to eliminate bogging.

Ron Woods Racing fits the front of the carb with an aluminum collar extending the neck length to fit the carb perfectly and allow a more secure mount with better flow since the collar butts right up against the intake manifold and no gap between the two exists.

Tuning is easy!
The idle mixture screw is on the left side.
The needle can be set by rotating the carb to clear the tank.
Pilot jets and pump nozzles are changed with bowl removal.
Main jets are change through the 17mm plug in the bottom of the bowl.

Jetting Baselines.


Idle mixture screw: 2 turn from seated, give or take a little.

Pilot: #30.

Needle: #97 (Standard on the 2nd groove from top).

Main Jet: 160 with snorkel tube, 150 without. (The main jet is the only thing to spend the dyno time on, and you tune for peak power with the sniffer helping to guide you the right direction.)

Accel pump nozzle: #50 (Squirting directly on the needle jet. You can turn it by reaching in with needle nose. Set to squirt from just off idle until 3/4 throttle.)



Main Jet Corrections, rules of thumb.
Altitude correction: Drop one jet (i.e. 152.5 to 150) for every increase of 1500'
Temperature correction: Increase one (i.e. 152.5 to 155) for every 15 deg. drop
Humidity correction: Increase one (i.e. 152.5 to 155) for every 15% drop

 

mine is doing the same thing at low rpm's cutting out plus itll shut down after about 5 mins of riding then it wont start for about 10mins

 

so many things contribute to carb problems, just a few things to make sure before diggin your carb, make sure ur air filter is clean, are u runnin an aftermarket one? are you doing this with the air box lid on or off, if its cuttin out a certain way and you have the lid on it might be starvin for more air, take ur lid off and see how it does. and make sure your air box tube - from air box to carb - is not collapsing when u hit the throttle.

 

ok well now to continue the circles im going in here... I took it out on the trails today to see what was going on. At first...with the engine cold, it seemed to run fine. The longer i was ou...ie the warmer the engine got the worse it would bog the cut out and jerk ect.. Almost to the point where if i even touched the throttle it would do it. No matter what rpm, holding it steady or advancing the throttle, so now im starting to think it's not the carb. Really frustrating. I appreciate any help.

BTW... North east Ohio not sure what the elevation is, today was 86 degrees out. the accelerator pump is working and is set to what the manual for the carb says it should be. I have a K&N airfilter & pre charger. No air box. And alba pipe with a super trap on the end. (which i dont like, sounds better with out the super trap)
Thanks,
Dave Brendorfer

 

I went through this myself with a recently installed HSR45 on my DS650. Fresh 12.5:1 piston, after market cams, Yoshi exhaust, Ron Woods CDI and carb mounted K&N filter. I jetted 150 main and 32 Pilot to start. Smallest accelerator pump nozzle and squirt adjusted to stop at 1/2 throttle. No matter what adjustments I made, the accel pump was just giving too much fuel. I pulled the accel pump rod out and the quad ran awesome - turns out it was just getting to much fuel. Easy way for you to test is lift the white cam up off the accelerator pump shaft and just pull the shaft out. Take 'er for a spin and see the difference in your bike. Don't forget to put something in the hole the shaft came out of to keep dirt out.

I really hesitated on disabling the accel pump due to recommendations from this site, but the quad runs great. I will have a slight stumble if I jab the throttle off idle - but it runs perfect otherwise.

As info, I ride sea level to 4500 feet and a 145 main with 40 pilot seems to be doing the trick.

Eric

 

I was starting to thing it was the accelerator pump as well but would that get worse as the engine got hotter?

 

It will get worse as the engine gets hotter if fuel delivery is excessive. My quad would start and idle great but would just bog while giving it moderate throttle unless I was real high in the revs at WOT regardless of pilot jet, pilot screw or needle settings. Since it's so easy to just slip the accel pump shaft out to test (if no difference, just put it back in - no tools or required) just give it a go. If that helps out your situation, you can then remove the accel pump return spring and get the lighter throttle spring from Ron Woods to give you a super easy pull on the throttle.

 

IM running the tm45 carb from Ron woods, mine didnt come from them with the accel pump at all. However i cent get mine to run correctly, so maybe thats why.
open air box w/ k&N, yosh pipe for now
I am goin to OMW this winter so ill get a lectron then with my motor...