High Altitude set up for Mikuni (2018)

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The carb was on the bike when I purchased it as a complete but non running bike a few months ago. So I am in the process of getting it operational. The carb is in good condition from an appearance standpoint and after disassembly it looks good internally as well. I just slid the needle jet out and it is 159-PO. I have removed these parts to inspect, clean and check the sizes. Should I switch this out for the 159-06?
 
I've used Carburetor Parts Warehouse in the past. Very quick turn around. My parts usually arrived within a week. www.carbparts.com/
That said, any good multi-line Japanese brand shop should have them
 
Thanks for the jet recommend. I installed today and the bike started easily and after adjusting the idle it feels great, throttle response is excellent, sounds great. So I’m confident the carb set up is good to go. However I noticed I now have an oil leak that is dripping from the cylinder fins between the head and the barrel right below the left exhaust pipe. About s drop every 5-8 seconds. Again this is a newly rebuilt head and rebore by James Comstock. Is this just a recheck torque settings or maybe a leak around the lifter opening? I used a composite gasket with no sealer.
 
Check rocker spindle covers for tightness also. Oil leaking from them can pass towards the front of the engine. If you are getting that much oil it is not likely to be the rocker cover.
 
As Batrider stated the rocker spindle covers are a good place to check. I had the same oil issue as you describe and had a bitch of a time getting the spindle covers to quit their seeping. New gaskets, copper sealing washers, and various types of chemical sealants slowed it but didn't stop it until I used Hylomar sealant on everything including the bolt threads. One more leak slapped to the curb.
 
batrider said:
Check rocker spindle covers for tightness also. Oil leaking from them can pass towards the front of the engine. If you are getting that much oil it is not likely to be the rocker cover.
Click to expand...
Bingo!! Rocker feed banjo nut was only finger tight. A new day, fresh thinking ancheckingmoff the easy stuff is always the proper course. Thanks for your advice!
 
Ok, I’m really pleased with the oil tightness of the motor! The new carb set up is wonderful the plugs now have a welcome gray cast. BUT, (shees it’s always something, right?) there is a sticky spot on the throttle and it is right at the the cruising spot. I have checked the cable for kinks, the twist grip, the handlebar thickness, the routing of the cable, and the slide inside the carb. I cleaned the twist grip looking for burrs or something that create stiction, I lubed the cable. Finally I started the bike (wow it ticks over nicely at 1000 rpm!), with the twist grip removed and just gave the cable a tug by hand and it still has stickyness. Has anyone else had a similar issue with their Mikuni? Should I replace the cable? There isn’t much clearance at the bottom of the top center frame rail and the top of the carb, is this a concern and is there something in the carb itself that might be the source?
Thank you!
 
lloyds-son said:
Ok, I’m really pleased with the oil tightness of the motor! The new carb set up is wonderful the plugs now have a welcome gray cast. BUT, (shees it’s always something, right?) there is a sticky spot on the throttle and it is right at the the cruising spot. I have checked the cable for kinks, the twist grip, the handlebar thickness, the routing of the cable, and the slide inside the carb. I cleaned the twist grip looking for burrs or something that create stiction, I lubed the cable. Finally I started the bike (wow it ticks over nicely at 1000 rpm!), with the twist grip removed and just gave the cable a tug by hand and it still has stickyness. Has anyone else had a similar issue with their Mikuni? Should I replace the cable? There isn’t much clearance at the bottom of the top center frame rail and the top of the carb, is this a concern and is there something in the carb itself that might be the source?
Thank you!
Click to expand...
If it's stiff opening the throttle by pulling on the cable then you have a problem with the cable or the slide,if it's not returning when your are riding you may want to put an amal throttle return spring inside the mikuni one, many people have had to do this with a single mikuni set up
Don't get too carried away with a slow Tickover your Norton will Tickover a lot slower than a 1000rpm but don't set it any slower and don't let it tickover for any longer than necessary,
Or your next post could be about premature camshaft wear cheers
 
I had the same problem with my single Mikuni setup. I replaced the cable and the problem went away. I cut the end off of the old cable and pulled it out thinking that I'd find a slight fraying. Nothing. When I pushed the cable back into the sheath it got a bit hung up. It appeared that it had gotten crunched about halfway down probably when I cinched the tank down against it. I've now routed the cable differently and I've had zero problems.
 
Some of the older type cables are not nylon lined like the modern Japanese type cables.
 
I just ran the bike down the road and I am happy to report that adding the Amal spring solved the problem thanks for your help!

QUOTE="baz, post: 389943, member: 2200"]If it's stiff opening the throttle by pulling on the cable then you have a problem with the cable or the slide,if it's not returning when your are riding you may want to put an amal throttle return spring inside the mikuni one, many people have had to do this with a single mikuni set up
Don't get too carried away with a slow Tickover your Norton will Tickover a lot slower than a 1000rpm but don't set it any slower and don't let it tickover for any longer than necessary,
Or your next post could be about premature camshaft wear cheers[/QUOTE]
baz said:
If it's stiff opening the throttle by pulling on the cable then you have a problem with the cable or the slide,if it's not returning when your are riding you may want to put an amal throttle return spring inside the mikuni one, many people have had to do this with a single mikuni set up
Don't get too carried away with a slow Tickover your Norton will Tickover a lot slower than a 1000rpm but don't set it any slower and don't let it tickover for any longer than necessary,
Or your next post could be about premature camshaft wear cheers
Click to expand...
 
1up3down said:
I live at 6000 feet altitude here in New Mexico and my single Mikuni 34 for my 850 is jetted
stock except for the idle circuit jet which I dropped to a 35 from the CNW supplied stock 40.
I check the plugs regularly and they are clean, I doubt you have a jetting problem.
If it has sat for a long time first put in brand new plugs then take the carb float off and clean it out
of any scummy gas accumulated there. You may also want to take your two gas tank petcocks out
and insure the filters are not clogged up. If your slide is in the middle notch it is fine for your altitude. I have ridden with stock jetting in excess of 10,000 feet altitude for short periods.

Can you tell us your Mikuni settings such as what size pilot jet, what notch is your slide clip in, what size main jet?
Click to expand...
Hello 1up
I'm in Colorado @ 7500'. Purchased the samecarb setup as you. What throttle cable did you end up using? Thanks!
Mofo
 
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