Rock solid sell big end bearings (well it lists it on their site as a spare) so you could give them a go if you already haven't.
However I don't see the huge deal over big end bearings - you are the first person I believe on this forum to have problems with them? My 10K RPM engines big end bearing is still fine after 3 kilometers of WOT riding and also some no load (clutch in) engine revs that my m8 insisted on doing lol (god knows how much RPM that got!) and I still have yet to have any bearing issues with my engine that runs stock bearings.
I think I can help you with balancing the engine.
First decide on your balance percentage. Most balance percentages are between 50 and 60%. Typically people use 55% - many gokart engine "pros" swear by very precise amounts like 54.3% and such which is rather a placebo percentage if you know what I mean. I recommend 55%.
Now you will need to weigh the total piston assembly - piston, rings, gudgeon pin - record this.
Now weight each end of the conrod with the corresponding bearing inserted into its race. Weight each end with the conrod in a horizontal position. 2 accurate scales are ideal but using one will work too. Record this.
NOW...
Add the piston assembly weight to the little end weight and times his amount by the balance percentage (keep in mined 55% equals 0.55).
Now add the big end weight to this number calculated above and the answer you get is your balance mass.
TO BALANCE the crank, make up a balance mass that weighs exactly as much as the balance mass calculated above. You can make it from anything - tape up nuts/bolts together is you want.
Fix this to the crank pin and mount your crank on 2 knife edge bearings that are level to the ground and parallel (2 steel rods will work) and now the fun part.
You have to removed enough metal so that when the balance mass is attached to the crank pin you can turn the crank along the knife edges and no-matter what position you leave it at, it wont roll over to the heavier side - if you know what I mean.
Then once done you can install your balanced crank CAREFULLY so you wont put it out of true - speaking of which the crank and all its components should be machined then assembled so that they spin true and concentric THEN you can go about balancing it. No point balancing a crank thats out of true.
In addition balancing is not as big of a deal as its all talked about for our engines - rather get the crank and counter balances machined concentric then true them up. Then seeing as our crank is already out of the engine you can balance if you want AFTER truing it.
Lastly this method WORKS as I've gone to the tip and brought a brush cutter and using this technique and a scale accurate to 0.01 grams I calculated the balance mass and once I attached it to the crank pin, guess what! It was balanced!
However I don't see the huge deal over big end bearings - you are the first person I believe on this forum to have problems with them? My 10K RPM engines big end bearing is still fine after 3 kilometers of WOT riding and also some no load (clutch in) engine revs that my m8 insisted on doing lol (god knows how much RPM that got!) and I still have yet to have any bearing issues with my engine that runs stock bearings.
I think I can help you with balancing the engine.
First decide on your balance percentage. Most balance percentages are between 50 and 60%. Typically people use 55% - many gokart engine "pros" swear by very precise amounts like 54.3% and such which is rather a placebo percentage if you know what I mean. I recommend 55%.
Now you will need to weigh the total piston assembly - piston, rings, gudgeon pin - record this.
Now weight each end of the conrod with the corresponding bearing inserted into its race. Weight each end with the conrod in a horizontal position. 2 accurate scales are ideal but using one will work too. Record this.
NOW...
Add the piston assembly weight to the little end weight and times his amount by the balance percentage (keep in mined 55% equals 0.55).
Now add the big end weight to this number calculated above and the answer you get is your balance mass.
TO BALANCE the crank, make up a balance mass that weighs exactly as much as the balance mass calculated above. You can make it from anything - tape up nuts/bolts together is you want.
Fix this to the crank pin and mount your crank on 2 knife edge bearings that are level to the ground and parallel (2 steel rods will work) and now the fun part.
You have to removed enough metal so that when the balance mass is attached to the crank pin you can turn the crank along the knife edges and no-matter what position you leave it at, it wont roll over to the heavier side - if you know what I mean.
Then once done you can install your balanced crank CAREFULLY so you wont put it out of true - speaking of which the crank and all its components should be machined then assembled so that they spin true and concentric THEN you can go about balancing it. No point balancing a crank thats out of true.
In addition balancing is not as big of a deal as its all talked about for our engines - rather get the crank and counter balances machined concentric then true them up. Then seeing as our crank is already out of the engine you can balance if you want AFTER truing it.
Lastly this method WORKS as I've gone to the tip and brought a brush cutter and using this technique and a scale accurate to 0.01 grams I calculated the balance mass and once I attached it to the crank pin, guess what! It was balanced!
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