Please forgive a noob on temperature questions

[tungxvu]

I am really new to these 2-stroke engines, and I have a couple of noob questions:

I have a 87 Spree that my friend gave to me. Here are the things we did to the bike.

a) My friend he installed a 48mm BBK he bought from Taz on Ebay. He did a very good job installing it since we got a compression of about 132psi.

b) I installed the jet (#90???) that Taz sent with the kit.

c) My friend already cut three one-inch-diameter holes on the airbox lid and retained the filter.

d) We did not modify the gears at all, but did a 128:1 premix in the gas tank and retained the oil injection pump.

Anyways, here are my questions:

1) The bike seems to bog down and * a little at around 20mph, and it will top out at about 24mph. I had to open up the air mixture screw a couple of turns, and the symptoms lessened significantly, but were not completely eliminated. The (new) plug seems to be running a bit rich since it looks kind of wet and black.

2) I started blocking off the three one-inch-diameter holes on the airbox lid, and found that reducing them to 1/2" in diameter would be much better. The bike can do about 32mph now and the hesitation/* is gone. However, another new spark plug still looks a bit wet and black.

3) I installed a temperature gauge - the type with a ring underneath the spark plug - and found that the bike is running at around 280F. Is this temperature OK, or is it an indication of a too-rich condition. Will it hurt anything if I keep running it at this lower temperature?

Thank you very much and please go easy on the new guy

[bonesv]

It sounds like you have everything correct but there may be a bit of a rich condition caused by the exhaust pipe possibly being a little clogged up? Can you verify the pipe as completely clean and un-clogged by oil/soot buildup? You could try running a hotter spark plug to help burn off the excess oil/rich condition? Are you running NGK spark plug? BR6HS? That should be correct plug. Your temps are on the cool side as 375-390 will be overheating. Maybe an actual Spree BBK owner/operator will chime in to help? Welcome to the Forum!

[tungxvu]

Hi Bonesv,

Thank you so much for your reply. I am running the NGK BR8HS. I have no idea what the difference is between that and the BR6HS plug except that the service manual calls for either one of them.

As for the exhaust pipe, when I shake it a lot of particles came out. I did the best I could but there does not seem to be a way to get rid of all the junk in there. Since my neighbor is a welder, I am thinking about cutting open the side to remove the soot and then ask him to weld it back together.

Thanks again and best regards

[motormike]

As for the exhaust pipe, when I shake it a lot of particles came out. I did the best I could but there does not seem to be a way to get rid of all the junk in there. Since my neighbor is a welder, I am thinking about cutting open the side to remove the soot and then ask him to weld it back together.

NO ! !....don't cut it open.
Burn it out by putting it in a bonfire, or on an old gas grill.
Once it has burned all the oil and carbon build-up, it will rinse out with a garden hose.
Some mild tapping might aid in the loosening of the burnt residue.
This method is covered in the "Wikispreedia" found on this board.

[tungxvu]

Thank you, Mike