No, 0.08mm -0.12, thats a big difference. With all due respect to all our contributers, I cannot find the basis of the 'standard' 0.05mm as there is so little official information on servicing. I found and official HONDA service page for GY6, and they recommended those measurements, and I have found that the 0.08 works best for me. You cant go by much of whats supposedly official info, for instance my owners manual say change oil at every 2000k, in the service schedule, a sticker in the air box says 1000k, and a sticker on the engine says 3000k, so who do you believe. Honda recommend it every 1000 MILES, so with synthetic oil you should be safe at 3000, but I do it at 2000 to be on the safe side.
Post by BillyGreen1973 on Jul 10, 2006 18:37:23 GMT
With all due respect to all our contributers, I cannot find the basis of the 'standard' 0.05mm as there is so little official information on servicing. I found and official HONDA service page for GY6, and they recommended those measurements, and I have found that the 0.08 works best for me.
I have heard a few people say they get better results from using a 0.08mm valve gap. The 'standard' of 0.05mm come from the service manual (page 41).
I would like to see the 'Official' service data. I'll have to go and find it!
If you have a scooter problem, and no one else can help, if you can find them, maybe you could hire the A-Team!
Is that an official Chinese manual billy? I will try to find the Honda site again, it took some finding before. I have not gone more than .08 myself, although I think some have split the difference and gone to .10, .12 seems excessive to me. On the other hand I would say 0.05 is the absolute minimum, so if it starts to close up its not leaving much tolerance.
You can set your gaps to 0.1mm (4 thou) no probs, but they will be ticky. 0.05 (2 thou) for both should be fine, check at various locations 'off cam' there's no telling if the cam is ground perfectly central & 0.05mm is a tiny clearance.
Do you still have your heatwave in sunny Brighton? Ours still has a few more months to run!!!!
I too have read BillyGreen1973’s guide and will be checking/adjusting my Baotian BT50QT-9’s valve clearances soon.
One thing the guide doesn’t show is how to access the engine with it still on the scooter. Can it be done by removing just the seat/helmet storage compartment or do you have to remove more bodywork?
Also, what is the commonest problem with these scooters? Is it the clearances reducing to zero or even a negative measurement so the valves don’t close properly, (I guess reducing compression)? Or, do the clearances increase causing the valves to open late and close too soon, (I guess increasing compression)?
Finally, what happens to the valve clearances when the engine warms up? Do they reduce or increase? This may help me with a problem I have been experiencing, see ‘Drive belt/Contra Spring’ in ‘Engine & Derestriction’.
PS One more thing! Am I right in thinking the 50cc 4 stroke in my Baotian BT50QT-9 is based on the Honda GY6? Someone please confirm!
The GY6 engine and other Honda engines are made in China for Honda by one specific Chinese manufacturer, I have lost the name in my mind with so many chinese names coming to light. I will post it if I find it, but the story goes Honda gave this company the legal rights after they copied it unoficially, then the Chinese company made the details avaliable to every other bloke and his brother, hence we now have some engines coming from as high-tech factories as the Japs could build, but equaly some one working from a shed with a lathe and buying in castings turning out 3 crappy engines a week! Quality control in most of the smaller companies is non existent! If you google some chinese manufacturing sites of which there are many you will see absolutley 100's of companies we never hear of chucking these things out. Most are crap, we seem to get the better ones due to the smaller companies finding it too expensive to produce to EEC regs. Keihin carbs are also made out there for the Jap. carb. company to go on named products like Honda, Suzi, Kawa, Yam. etc. Caterpillar, Ford, Perkins engines and Aircraft companies to name but a few all have factories out there too.
I have finally got around to checking the valve clearances on my Baotian BT50QT-9.
After removing the seat/helmet storage box, access to them was made easier by removing the panel in front. Two screws just beneath the rubber mat, then it unclips and slides away.
I found the guide very useful, although there were four marks on the flywheel. I went for the one nearest the T mark. I also needed to turn the flywheel one further full turn to get the large hole on the engine cog at the top.
When I went to check the clearances, I found the arms did move a bit. I checked/set the clearances with the gap at its largest. Is this correct? I found my .05mm feeler would not slide in the highest valve’s gap, but would the lowest. Having just .05mm, .07mm and .10mm feelers, I opted to use the .07mm and set the adjuster/tighten the lock nut with it in place. The .07mm slid in and out, but not the 0.10mm.
Unfortunately, this appears not to have solved my problem with loss of power/acceleration once the scooter is warm, see ‘Drive belt/Contra Spring’ in ‘Engine & Derestriction’. At least it is another thing eliminated.