How to seal carb holders to intake flanges

[shizznats]

We were toying with our LTD engine some more yesterday, and after starting it one time, the revs shot up to redline very very quickly. We shut the engine off as soon as we could and were trying to figure out what had happened. I hadn't messed with the carbs before then so my first thought was some kind of air leak. We had applied a non-hardening pliable Permatex sealant between the carb holders and the intake flanges on the cylinders a while back to prevent air leaks there and noticed that at the top of the carb holders, there was a slight gap and when we pushed on the carbs, a bit of liquid would appear in the space between the carb holder and the intake flange. I assumed this could be our problem, so we removed the carbs and unbolted the carb holders which were stuck on there pretty good. To my surprise, most of the sealant we had put there was gone  This stuff was supposedly gasoline, oil, and heat resistant (Permatex #2). I hope this is our issue and that it's not an air leak elsewhere.

The manual says to put the carb holders on dry... but that seems like asking for an air leak. Especially since we have aftermarket carb holders which may not seal as well. Do you guys use any sort of sealant or gasket when putting on carb holders? Thanks!

[mswyka]

Mike, some of the lower quality holders can bend easily and if bent will gap in the middle.  JDMatt has some genuine Mikuni holders - these are recommended.  I made the mistake of using RTV on my first holders - but it didn't stay.  I now use a thin coat of permatex no. 2 and they seal well.  On the thinner holders I have also had some success by pre-bending them so that they are convex towards the engine intake.  Then as the bolts are tightened they are pulled flat.  I was able to run two sleds that way for a few years.

[Lloyd (ljm)]

 
  I have given up trying to seal aftermarket carb boots.

 Genuine Mikuni boots seal and last much longer.

 I have been very happy since I started using Them.

 I have melted a motor that had brand new aftermarket boots.

 newbreedparts.com   Carries both aftermarket and genuine Mikuni boots.

 Lloyd

[Lloyd (ljm)]

 Hey Mark

 I was typing as you posted...

[shizznats]

Thank you for the great info! Will the genuine Mikuni boots fit our Keihins??

[Lloyd (ljm)]

 You can sent JDMatt a message. He is a member here. He owns Newbreedparts and runs the JDsleds.com website.

[gixxer6]

The last Mikuni boots I recieved from DennisKirk were exaclty like the cheapo boots.  They came sealed in a Mikuni bag...  I will only run OEM Arctic Cat boots...

[shizznats]

Thanks! What do you guys torque the carb holder bolts to? It seems that over-torquing these could cause them to bow and create a gap in the middle perhaps?

Edit: Apparently the manual says to torque these to 45 in. lbs... which if I'm not mistaken is 3.75 ft. lbs. Is it just me or does that seem very very low? I know mine were torqued way more than this and perhaps that caused the issue?