Engine quits in hot weather

[steve beddow]

I have a 1988 SB50P
I Just put in 44mm kit. (new piston new cylinder new piston pin new clips, new rings) It's 110 degress here. I've put almost a hundred miles on the scoot for brake in purposes. Now new owner rides her across town 15 miles trying to keep it under 30mph. suddenly the bike quits. But will start up in a minute or two. Goes a mile or so and quits. again starts up. this happens several times. Then when she slows down to under 20mph It runs good. There is no drag on the engine like it gets real hot and locked up.Ps the new owner weighs close to 220lbs. Are we asking too much out of the scooter and it needs to be driven slower at these high temps? What about adding a little 2cycle oil to the gas in this hot weather. Will adjusting the air mixture neddle in a little ( for cooler running exhaust)

[Trafficjamz]

I have a 1988 SB50P
I Just put in 44mm kit. (new piston new cylinder new piston pin new clips, new rings) It's 110 degress here. I've put almost a hundred miles on the scoot for brake in purposes. Now new owner rides her across town 15 miles trying to keep it under 30mph. suddenly the bike quits. But will start up in a minute or two. Goes a mile or so and quits. again starts up. this happens several times. Then when she slows down to under 20mph It runs good. There is no drag on the engine like it gets real hot and locked up.Ps the new owner weighs close to 220lbs. Are we asking too much out of the scooter and it needs to be driven slower at these high temps? What about adding a little 2cycle oil to the gas in this hot weather. Will adjusting the air mixture neddle in a little ( for cooler running exhaust)

Did you rejet when you put the BBK in?

The Bigger bores need more oil than the stock pump can handle. Add an ounce to the tank to be on the safe side.

It sounds like it is soft seizing to me.

[Bear45-70]

I have a 1988 SB50P
I Just put in 44mm kit. (new piston new cylinder new piston pin new clips, new rings) It's 110 degress here. I've put almost a hundred miles on the scoot for brake in purposes. Now new owner rides her across town 15 miles trying to keep it under 30mph. suddenly the bike quits. But will start up in a minute or two. Goes a mile or so and quits. again starts up. this happens several times. Then when she slows down to under 20mph It runs good. There is no drag on the engine like it gets real hot and locked up.Ps the new owner weighs close to 220lbs. Are we asking too much out of the scooter and it needs to be driven slower at these high temps? What about adding a little 2cycle oil to the gas in this hot weather. Will adjusting the air mixture neddle in a little ( for cooler running exhaust)

Did you rejet when you put the BBK in?

The Bigger bores need more oil than the stock pump can handle. Add an ounce to the tank to be on the safe side.

It sounds like it is soft seizing to me.

+1

[steve beddow]

I used the jet that came with kit but it was the same # as the orginal carb. The kit also suggested I drill several 1 inch holes in the filter which I did but it wouldn't run for * so sealed up all but one.

i will try adding oil

I'm open to other suggestions. Including a statement like--YOU IDOIT THESE SCOOTERS ARE NOT DESIGNED TO RUN IN HEAT LIKE THAT AT ALMOST FULLSPEED











3 as

[Wheelman-111]

Greetings:

Quoth Steve B:

I'm open to other suggestions. Including a statement like--YOU IDOIT THESE SCOOTERS ARE NOT DESIGNED TO RUN IN HEAT LIKE THAT AT ALMOST FULLSPEED

That is in fact exactly what they are designed to do if everything is right. All day long, until the tank runs dry. However since yours isn't stock anymore, something may be wrong.
I have no experience with the 44mm BBK, but installation is the easy part of any BBK. Setup is key. What static compression did you measure on assembly? What is it now? What size is that main jet? If it's a 68, you may need more. Before further attempts at running this engine, I suggest you search "vacuum Leak" and follow procedures suggested by that search.

[Trafficjamz]

did you match the head to the bore?

[bakaracer]

if the compression is to high, no matter what jet you put in there its going to run hot, knock and seize. if the head wasn't cut to the size of the bore, thats one problem. get that problem fixed first then you will have to check the compression and see where your at ,then go from there. if the head isn't cut to size, get it cut and then you will have to get the squish band in the head redone also. have them cut it to a 14deg angle if possible.