Motor Kit Advice?

[Tressie]

Stud replacement?

I read somewhere that the studs for the head, intake and exhaust are pretty poor spec, and should be replaced first thing.

If I cut-up some high tensile strength steel bolts to fit, then what should I use to glue them into the cylinder? I hear Loctite won't handle the temperature.

T.

 

[Deleted member 12676]

the temp isn't too high for Loctite.
as far as rpm limiting, 2 strokes limit the rpm by the height of the exhaust port. too complicated to fully explain here. click on my signature link and lick on the link for "porting for peak rpm". the authorities go mostly by engine size and top mph (or kph in your case). These engines aren't marked as to their size. They won't put your bike on a dyno to check for how much horsepower it has. So you can increase the power w/o increasing the maximum speed.

Yes, if you don't correct engine vibration you will need stronger nuts/bolts and Loctite. Also you'll need to replace the upper conrod bearing after a year since the extra compression psi caused by too advanced ignition at top rpm will destroy the stock bearing. the replacement bearings are better.

 

[Tressie]

the temp isn't too high for Loctite.
as far as rpm limiting, 2 strokes limit the rpm by the height of the exhaust port. too complicated to fully explain here. click on my signature link and lick on the link for "porting for peak rpm". the authorities go mostly by engine size and top mph (or kph in your case). These engines aren't marked as to their size. They won't put your bike on a dyno to check for how much horsepower it has. So you can increase the power w/o increasing the maximum speed.

Yes, if you don't correct engine vibration you will need stronger nuts/bolts and Loctite. Also you'll need to replace the upper conrod bearing after a year since the extra compression psi caused by too advanced ignition at top rpm will destroy the stock bearing. the replacement bearings are better.

Hi Michael,

Ah, thats the sort of info I had been hoping for. You've obviously gotten right into 2-stroke engines, so I suspect you're the man to ask.

Okay, if you we going to de-tune a 48cc HT in order to limit it's output to around 200W, then how would you tackle the operation? On the one hand, there's a (pricey) commercial kit that comprises of 'matched' air filter, intake port and exhaust port constrictions, along with unknown carburettor adjustments for smoother bottom end. Now having taken a brief look at the resources you had suggested, it appears a more favourable result might be obtained by way of exhaust port modification.

T.

 

[Samdallas214]

if there is any way you can afford it go American made the kits cost far more but are far better kits.

I see you are on ebay just stay away from eBays boygofast he sells junk beware spend a little extra and go with a different seller even if you get it off eBay

 

[Deleted member 12676]

JNMotors is preparing to sell improved engines but really if you take my advice and do it yourself you will have more pride in your machine as well as having increased your experiential knowledge.
I don't think they need to be detuned. they already are. that's how they pass all govt regulations. they wont/cant know the actual power output so they just go by engine size (which they wont measure to verify) and top mph. So I say make it more powerful but dont raise the exhaust port so much that you can exceed the speed limit for them.

 

[Samdallas214]

JNMotors is preparing to sell improved engines but really if you take my advice and do it yourself you will have more pride in your machine as well as having increased your experiential knowledge.
I agree.



I don't think they need to be detuned. they already are. that's how they pass all govt regulations. they wont/cant know the actual power output so they just go by engine size (which they wont measure to verify) and top mph. So I say make it more powerful but dont raise the exhaust port so much that you can exceed the speed limit for them.

I agree.