pr0blumz Posted September 22, 2009 Report Posted September 22, 2009 During a leakdown test, the lower left bottom bolt on the left side of the motor has air coming from around it. I've tried everything and can't get it to seal. That the only place i have air coming from. What do you guys recommend? Thanks Quote
JMADD Posted September 22, 2009 Report Posted September 22, 2009 During a leakdown test, the lower left bottom bolt on the left side of the motor has air coming from around it. I've tried everything and can't get it to seal. That the only place i have air coming from. What do you guys recommend? Thanks I've got the same problem as we speak on my 421. Both intakes leak. The air is getting in between the inner metal layer of the boot, and the outer rubber layer. I put some yamabond on the entire surface of the intake boot. It helped some, but it still leaks down to about 3 lbs in about 3 minutes. I may have another leak somewhere, not sure. I'm gonna run mine as is. I have one more race this year. Probably investigate the leak further over the winter. Quote
pr0blumz Posted September 22, 2009 Author Report Posted September 22, 2009 I've got the same problem as we speak on my 421. Both intakes leak. The air is getting in between the inner metal layer of the boot, and the outer rubber layer. I put some yamabond on the entire surface of the intake boot. It helped some, but it still leaks down to about 3 lbs in about 3 minutes. I may have another leak somewhere, not sure. I'm gonna run mine as is. I have one more race this year. Probably investigate the leak further over the winter. Mine is a 421 also. Mine leaks down at about a pound a minute as well. Quote
jbooker82 Posted September 22, 2009 Report Posted September 22, 2009 I guess cub cylinders are junk just like the boss intake since they leak too. Could it be coming from inbetween the threads of the bolt and hole? Like if the bottom of the bolt hole is opean to the intake tract? If so you might try some type of thread sealer. Quote
pr0blumz Posted September 22, 2009 Author Report Posted September 22, 2009 I guess cub cylinders are junk just like the boss intake since they leak too. Could it be coming from inbetween the threads of the bolt and hole? Like if the bottom of the bolt hole is opean to the intake tract? If so you might try some type of thread sealer. Yeah, Kevin sold me junk cylinders....ha! I thought about using thread sealer but I was running out of time before I had to go to work. I put some black silicone off in the bolt hole and I'm going to let that sit and dry until I get time to check it again. Quote
JMADD Posted September 23, 2009 Report Posted September 23, 2009 If they're like mine, the leak isn't coming around the bolt itself. It's leaking between the layers of the intake boot, and it just escapes around the bolt holes in the intake where the rubber is cut out. Silicone on the treads doesn't help mine. Quote
jbooker82 Posted September 23, 2009 Report Posted September 23, 2009 You might try going to the hardware store and get some rubber washers and regular flat washers. Sandwitch the rubber washer between the intake boot and the flat washer. Quote
JMADD Posted September 24, 2009 Report Posted September 24, 2009 I may try that. The yamabond didn't fix it. Quote
pr0blumz Posted September 24, 2009 Author Report Posted September 24, 2009 If they're like mine, the leak isn't coming around the bolt itself. It's leaking between the layers of the intake boot, and it just escapes around the bolt holes in the intake where the rubber is cut out. Silicone on the treads doesn't help mine. I found out mine is leaking the same way. I'm going to try injecting some black silicone in between those those two layer and see if that helps. Quote
dajogejr Posted September 25, 2009 Report Posted September 25, 2009 Interesting read guys...I just put UPP on my bike after battling a leak on my boss intakes. And I leak tested mine after, less than a lb or two after 6 minutes...been riding it all year since. I'm going to Chariot intakes next. he's local...and makes nice stuff! Quote
rubberneck Posted September 25, 2009 Report Posted September 25, 2009 i have 2 sets of white knuckles and so far they are tight as a frogs ass Quote
pr0blumz Posted September 25, 2009 Author Report Posted September 25, 2009 Ok, I fixed the air leak. Now, I messed up my gaskets on that side by take them off so many times. I tried doing a leakdown test right after putting some silicone in place of both gaskets on that side but I kept getting an airleak. Should I wait until the glue has set for w while or do I need to use gaskets? Quote
dajogejr Posted September 25, 2009 Report Posted September 25, 2009 Both. Use the gaskets, use the RTV and give it 24 hours to cure. Normally, you can bolt it right up and run it. Since you're having issues....sealing issues, give the RTV time to cure. Quote
JMADD Posted September 25, 2009 Report Posted September 25, 2009 I found out mine is leaking the same way. I'm going to try injecting some black silicone in between those those two layer and see if that helps. I may try the black silicone before I change out my intakes. I have another set of UPPs and some newly siliconed Boss intakes also (which I'm aware of the issue with those.) Dave - the UPP intakes don't leak until after lots of abuse from the carb bouncing around. Your's should be fine for a long time. THese that I have are about 3 years old. Quote
dajogejr Posted September 25, 2009 Report Posted September 25, 2009 As much as I'd like to say the motor will be for sale after this year to go bigger, I just don't see it happening. It's paid for, reliable and fun...so...I'll have to keep an eye on these for a while... The leak down test kit I bought last year has not only saved my motor this year, but saved a buddies when he had a ton of epoxy leaks in his cases... They are truly an invaluable tool! Quote
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