26 zen ported having issues??

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bajamaniac69

Well-Known Member
Messages
139
Location
Florida
No more issues .....it was a loose carb bolt!!!!!


Hey guys ...Just wondering...I have a zen 26 ported and machined from badboy (pete)....

it has 3 tanks on it...cant get idle down...have to turn Low speed to 2 1/2 turns out and idle out almost all the way.....I put a new carb on it .....samething....still idles high....changed all gaskets as well....

Please help......any ideas>???

Thank
 
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check the cylinder gasket below the exhaust. sounds like an air leak, and loose cylinder head bolts, can cause this. also the cylinder gasket (depending on what was used) tends to blow out between the 2 bolts.


look the motor over well. you ll likely find a bad/blown cylinder gasket, or an air leak somewhere. carb/intake/cylinder gaskets, loose spark plug, or cylinder or exhaust bolts, ect....
 
cooper gasket under head ...metal intake gasket...changed carb gaskets......cylinder bolts are tight....I don't know!!!!!!!!!!!...

:helpsmilie::helpsmilie::helpsmilie::helpsmilie:
 
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Spray something like wd40 around the head and carb gaskets and see it it effects it. I would think there is a leak somewhere too. Are you sure the throttle is completely closed?
 
New gaskets..put together dry?..paper or copper?..you have a air leak...
you need too use a gasket sealent.....I like to use Permatex #2..apply a dab to coat
the gasket..bolt your lower case half's tohether..you cylinder..make sure you torque
your bolts....possiable oil seals leaking.....that will cause a air leak....If the bakealite
or plastic intake..that can warp if tightened to tight.....Just my opinion here.................Slawhammer
 
You bet...thats a air leak....always when rebuilding a engine...Run it for say 10 minutes
retorque the head bolts....I do this my self ..at least 2 times..just to be sure..there
tight...They will come looseon first running of a rebuild engine.....Slawhammer
 
You know there are 3 adjust screws ..Correct...
2 small ones up high on the carb..1 silver bigger screw,,lower down..,That's the idle adjust..
the higher screws are H&L adjustment... ..I want to see a photo of your carb screws..
I think your going at it wrong for adjustments....Just my opinion...Slawhammer
 
did you use any sealer on the copper cylinder gasket? or just put it on?

the copper gaskets MUST have a sealer used like Permatex ultra copper, or Yamabond ect...

check all the bolts, carb throtle shaft also.
 
I checked the carb arm and the bolts....all is snug......Igot the motor used from Pete on this forum.....I am not sure ...he said he ran it for 3 tanks no issues....

I put a cooper gasket on exhaust port ....Would this cause enough of a air leak to create this problem....I did not use any sealant on that gasket ....


Slawhammer......I realize the settings on the carb...I have 1.5 on the high speed needle and 1.25 on the low......idle screw is set correctly ......just revs high if I turn the low speed counter clockwise 2.5 turns it comes down ....but I don't see this being right as base settings are 1.5 h and 1.25 low....even if it is a ported motor,2 on h and 1.50 L should be ok...
 
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your High & low settings should be ok..H1.5 L 1/1/4 sounds like air leak..
i my opinion..all gaskets need a sealent...slawhammer
 
the exhaust gasket wont hurt but it'll leak if you don't use sealer like the permatex copper stuff..try spraying wd40 around the clutch to check the crank seal for leaks.

if it'll stay running with the low all the way out then it's pulling a lot of air from somewhere
 
i say this because its happened to me.


when you put the exhaust on. are you Sure you got both bolts THRU the holes on the exhaust gasket? on two occasions, while doing work on mine, i missed one of the holes and the gasket slipped down, opening it up to air. i caught it both times before i started the motor up, but had i note gone over them taking a good, carefull look over, i would of missed them both times.

may be worth a look.
otherwise, ya even on a well modified motor, 1 1/4 out on the low is usually a bit too much. not in every case, but in the majority of them.

check your linkages are correct. the idle screw is hitting the throtle arm? adjusting it makes no differance?

one last thing, i have a 668 here that worked great for ever. its actually the original 668 o got on my 06 rtr baja. just last fall. it started to idle high for some reason. couldnt figure it out and nothing seemed to make a differance.
so i yanked the motor expecting to find a bad gasket or some other airleak like from a hole in the input gas line. nope none of that, so i narrowed it down to the carb. looked it over but never seen anything funky. tossed on a 813 i had here. first time i tried one.
a couple weeks later, i started to check the carb over.

after a while i seen something i had never noticed before. in the throat of the carb (other wise known as the venturi), just to the lower side of the body, right where the throtle plate was almost closed, there was a bur of some sort. it looked like the plate, somehow pushed up a small piece of the wall of the venturi, and created a stop. so when the carb went back to idle, it would rest against this stop, instead of fully closing until it was on the idle screw.

weird one. not sure how that bur came to be. nothing in the motor or pipe???

maybe worth a gander.

only thing ive seen work for exhaust gasket is a Red High Temp silicone/rtv type caulk wingnut uses. it was firm, but somewhat plyable when dry. and really seamed to help and didnt appear to burn out.
i ll find out what it is when i can and let you guys know.

without the exhaust gasket, it can pull in additional air in the scavange phase of the pulse wave thru the pipe. the extra air ofcourse can/will increase rpms from running leaner.

also check the headgasket under the pipe. i just rebuit a 30.5 that didnt like the 1st 2 gaskets, but the head bolts were viberating loose and i didnt notice it until the idle jumped up and i got to looking close at why it went up.
 
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