intake manifold bolts
Elite HDF Member
Joined: Sep 2007
Posts: 4,468
Likes: 12
From: Bluffton, South Carolina
For a Mikuni check all the same things except they do not have a diaphragm operated slide. Also the air screw works the reverse( the more you open it the more air you let in), if you tun it out more than 2 1/2 -3 turns from closed and it doesn't change the idle then you are too rich. Set the pump rod at .080" to start and try going larger first, you shouldn't have to go any closer than that running gasoline. If you get it too close it will cause a "sag" in your torque curve. We usually use a 20-25 pilot jet on an 80" EVO 160 main with the stock needle in the center position. a 22.5-27.5 pilot and a 165-170 in an 88" twinkie with the same needle configuration. Moving the needle up or down only affects about 3,000 RPM and up or about 70MPH plus. To change mid range you need to change needles, not raise or lower them.
Before you do any changes ensure that you have a good ignition and engine( compression, Leakdown, timing, valve adjustment, proper exhaust, Etc.), remember to check the float level as these carbs are shipped from the factory and the float level can change, and jets and jet tubes can be loose. Remember you cannot make up for too much cam with jetting, you will have reversion that varies with RPM and it will drive you crazy. Trust me on this as it drove a younger version of myself crazy until we figured it out.
If you roll off of the throttle and operformanceimproves thenthe main jet is too small, if you get back on it then the accelerator pump comes into play and everything changes. Try downloadingthe Mikuni HSR Tuning Manual it will help.
Last edited by miacycles; May 24, 2009 at 07:25 AM.
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Tourer
Joined: May 2009
Posts: 401
Likes: 19
From: Middleboro, MA USA
Just an FYI here...
To get the intake manifold bolts off and back on I took a 1/4" allen with a ball end and heated and bent the ball end to fit just right into the allen head screws. Now it worked to get them off, but the allen wrench barely had enough life left in it to tighten them back on again.
Might have been the fact that I used a cheap no-name allen wrench that I got from Lowes, but I am thinking getting the wrench red hot with the torch while bending it weakened it too much. The ball head twisted and after the first use was mangled and rounded. I had to file the head to get it to fit into the bolts again when putting them back on. I could have easily snapped the ball off into the bolt while tightening if I wasn't careful.
Just thought I'd put that out there.
To get the intake manifold bolts off and back on I took a 1/4" allen with a ball end and heated and bent the ball end to fit just right into the allen head screws. Now it worked to get them off, but the allen wrench barely had enough life left in it to tighten them back on again.
Might have been the fact that I used a cheap no-name allen wrench that I got from Lowes, but I am thinking getting the wrench red hot with the torch while bending it weakened it too much. The ball head twisted and after the first use was mangled and rounded. I had to file the head to get it to fit into the bolts again when putting them back on. I could have easily snapped the ball off into the bolt while tightening if I wasn't careful.
Just thought I'd put that out there.
Thread Starter
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Tourer
Joined: May 2009
Posts: 401
Likes: 19
From: Middleboro, MA USA
Thought I'd come back to this and report that I finally got the carb tuned in pretty good. Did it last weekend.
I ended up with this set up:
I took out most of the dynojet parts except the DJ accel pump and I'm still using the drilled slide.
Now I have the jets at 45/170 with 2 shims on the stock needle. I'm using the stock emulsion tube and I'm about 2 1/4 turns on the mix screw. Seems to be just about right. No more coughing after it's warmed up a little and it seems to warm up quicker now. I also repositioned the accel pump to squirt into the middle of the carb instead of towards the bowl drain tube.
Thanks again for all who tried to help out and especially t150vej, who was nice enough to take some time offline to help me get to the bottom of this.
People like you all are why HDF is my favorite forum.
Thanks
Chris-
I ended up with this set up:
I took out most of the dynojet parts except the DJ accel pump and I'm still using the drilled slide.
Now I have the jets at 45/170 with 2 shims on the stock needle. I'm using the stock emulsion tube and I'm about 2 1/4 turns on the mix screw. Seems to be just about right. No more coughing after it's warmed up a little and it seems to warm up quicker now. I also repositioned the accel pump to squirt into the middle of the carb instead of towards the bowl drain tube.
Thanks again for all who tried to help out and especially t150vej, who was nice enough to take some time offline to help me get to the bottom of this.
People like you all are why HDF is my favorite forum.
Thanks
Chris-
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