Gobbler Posted September 15, 2004 Report Share Posted September 15, 2004 Hi guys, My motor's got a air leak which is causing it to run lean up high in the rpm's ans splutter etc. I've just recieved a full gasket and seal kit from vito's performance ( top mob ) but was wanting to know if I can change all the motor seals out without having to tear the engine down to much. From experience, does anyone know if its more likely for the seals to go before the gaskets and let air in the motor ? Im hoping to do a quick fix ( like the seals only ) so I can get out and ride. Im not really to keen on splitting the gearbox apart if i dont need to. Any comments/suggestions or advice would be greatly appreciated before I rip into this Quote Link to comment Share on other sites More sharing options...
J.J. Posted September 15, 2004 Report Share Posted September 15, 2004 I recommend you perform a leak down test before you go any further. leak down test 1 leak down test 2 leak down test 3 Quote Link to comment Share on other sites More sharing options...
boonman Posted September 16, 2004 Report Share Posted September 16, 2004 I recommend that if you find an air leak, either replace the gasket, or if it is a crank seal, you need to pull the engine. Splitting the cases and re-sealing an engine is a job that can be done in one evening. From raining the fluids, to filling them up........ Just make sure you have Yamabond, and a GOOD torque wrench to put it back together...... Quote Link to comment Share on other sites More sharing options...
Gobbler Posted September 16, 2004 Author Report Share Posted September 16, 2004 Thanks Boonman. I'm trying to get some gear together to conduct a leaktest but its bloody hard to find the stuff were I am. I was hoping to replace all the seals and gaskets to eliminate the problem without doing a test. I have gasket kit, and seals plus some tight joining surface gasket silicon which I persume is for the gear case. Also rebuilding the carbs with all new parts and gaskets will hopefully eliminate them. I'll just rebuild the engine tonight and see how it goes in the morning Quote Link to comment Share on other sites More sharing options...
Gobbler Posted September 17, 2004 Author Report Share Posted September 17, 2004 (edited) Guys I tried a leak test but Im getting different results each time. Its beginning to really shit me. I blocked both exhaust exits, and made up plates with fittings to bolt over the read cages because that was going to be easier than finding pipes and fitting to use the carby boots. Anyway, whats happenning is with the first test ( im pressurising becasue I cant get hold of a vacum device here ) I pressurised to 6psi and in the 6 mins it dropped about 1 psi. In the second test, it dropped 1/3 of a psi and in ten mins and in the third test, it dropped 1/2 bar in 10 mins. With those results, is that acceptable or not ? I dont know waht the range is so to speek for leakage or is no leakage what we are after here ? Im starting to wonder if the reads are buggered ( They do look ok but im no pro on them ) or if I have blockages in the carbs, but ive cleaned them many times. Can anyone help me with this plz.. Edited September 17, 2004 by Gobbler Quote Link to comment Share on other sites More sharing options...
J.J. Posted September 17, 2004 Report Share Posted September 17, 2004 Make up some soapy water, apply the pressure and paint the soapy water over all the gaskets, seals and joints you can find, first check your test device connections, the plugs on the exhaust, the plates on the reedcage, the hose, the pressure gauge, everthing. The bubbles are normally easy to see and hard to miss. It should hold 6 psi about 1/2bar for 6 minutes, do not pressurise higher than this. Any loss of pressure of more than 1psi in 1 minute is a problem. If the test equipment is air tight, check the engine, base gasket, case joint, etc Next, check the right hand crankseal for leaks at the fitting for the gearcase breather, no air should leak out that hose. Finally, if you are sure there is a leak, but you haven't found it, remove the flywheel cover and the flywheel and check the crank seal behind the flywheel also. Later J.J. Quote Link to comment Share on other sites More sharing options...
Gobbler Posted September 17, 2004 Author Report Share Posted September 17, 2004 Thanks for the replt J.J. I did the soapy water trick and didnt find a thing. I've also removed the cluth cover and tried to get find a leak on the crank seal on that side but didnt. A few more tests later and Im still only dropping 1/2 to a 1/3 psi in 6 mins. It's pretty late herer now so tommorrow im goling to check the reads and carbs. Hopefull thats goin to be it. Quote Link to comment Share on other sites More sharing options...
boonman Posted September 17, 2004 Report Share Posted September 17, 2004 Sounds like you are holding a good seal in there..... The reeds could be screwed up, but that would make it bog in the upper RPM's, and drop off that cylinder when the R's get up there..... I had a cracked reed, and the bike wouldn't go past half throttle. And the cylinder stoppped firing..... Now, if your holding air, and all seems well at the moment, perhaps the leak could be in the carb boots. I had an air leak once, it was in the boots. I leakdown tested it, several times, and it held fine..... However, new carb intake boots, made her run like a champ again. Just a thought there...... May be a place to start..... Quote Link to comment Share on other sites More sharing options...
Gobbler Posted September 17, 2004 Author Report Share Posted September 17, 2004 Thanks boonman again. I'm going to check these reads and look right through the boots like you said. I suppose it won't be that bad just to replace the reads and boots now. They are 3 years old. Quote Link to comment Share on other sites More sharing options...
J.J. Posted September 18, 2004 Report Share Posted September 18, 2004 Thanks for the replt J.J. I did the soapy water trick and didnt find a thing. I've also removed the cluth cover and tried to get find a leak on the crank seal on that side but didnt. A few more tests later and Im still only dropping 1/2 to a 1/3 psi in 6 mins. It's pretty late herer now so tommorrow im goling to check the reads and carbs. Hopefull thats goin to be it. No worries... I bought these from UPP, they had no problem shipping to South Africa, so I'm sure Oz won't be a problem. Gobbler, where you from? I have a sister that lives in Perth and more family in Brisbane. Quote Link to comment Share on other sites More sharing options...
Gobbler Posted September 18, 2004 Author Report Share Posted September 18, 2004 P.M'ed J.J Quote Link to comment Share on other sites More sharing options...
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