'86 Spree: Engine rebuild/break in help.

Borsch · Post by **Borsch** » Tue Sep 04, 2007 10:37 pm

A couple of weeks ago I found a nice 86 Spree for sale for $350. Everything was great... or so I thought! I didn't give it a thorough look over when I bought it as I assumed I would be doing work on it; besides, I didn't have my socket set with me... even if I did, I'm sure the owner wouldn't be happy with me tearing apart his scooter right in front of him! What I found when I got it home was alarming!

I noticed that the head and engine block were covered with charred goo when I took the panels off. I decided to go for a ride and listen to the engine. I didn't hear anything that sounded like a blown head gasket, but it was topping out at around 20mph. I took it home and looked some more and found that it had no air filter element at all! I stuffed an old lawnmower foam element in, thoroughly cleaned the carb, checked the fuel and oil systems and everything seemed like it should be fine so took it for a longer test ride. After that bit of tweaking I had trouble adjusting the idle and it started hard, but I finally got it about right. speed was about 25mph but with some backfiring and no low end power until about 13mph. After that test run I figured that the exhaust was plugged which would account for the lack of power and hard starting (too much backpressure?).

The next morning I could see oily nastiness running over the crankcase. I decided that before doing any engine work I should check/clean the plug and do a plug chop and also make sure the source of the leak was the engine block (though I was sure it was). The plug looked a toasty, light-brown color (it was an old plug though so I'm not sure how accurate this is) the color was fine, right? Power and speed steadily got worse and it kept leaking sludge onto the head.

Well, I ordered new rings, new cylinder gasket and head gasket, A new piston pin clip (why didn't anyone tell me that they "shoot" outta there like a bullet?) and a filter element. When I opened it up the head gasket was intact and had a mostly clean seal... The base gasket or cylinder gasket was destroyed! the piston and combustion chamber where caked with carbon and there was some carbon build up in the exhaust port. Hours with a soft brass brush and parts cleaner has everything looking great. The piston is fine with only slight wear on the exhaust port side.

I think that maybe after so long without an air filter all that hot running just cooked the gasket? I know a compression check would have come back crappy, but I wish I had done one anyway. Running that lean should make the engine run hot right? what would it do to my compression?

I just wanted to know what you guys think happened and do you think a rebuild will solve the problem? Once i get her put back together, how do I break in my new-ish engine, or do I not need to?

Sorry for the extra long story and thanks for your time!

-Borsch

hondaman · Post by **hondaman** » Wed Sep 05, 2007 12:09 am

If the cylinder walls are clean and smooth and not all scratched up or pitted you will probably get away with just replacing the piston and rings. If not, the cylinder may need to be honed or bored. If you need to do that then you will have to go up a size on the piston.

hondaman · Post by **hondaman** » Wed Sep 05, 2007 12:13 am

As far as the break in period goes I would vary your speed for the first hundred miles. Do not take it on real long runs going wide open. Shorter runs going fast for awhile and then slowing down would be the best. The rings need a chance to seat themselves properly within the cylinder.

Borsch · Post by **Borsch** » Thu Sep 06, 2007 12:59 am

The engine break in period sounds do-able enough. I think I'm going to go with the old piston because with only a couple small rub marks it still seems to be in fine shape; also the cylinder is flawless so the piston can't be too bad.

Considering the 4,200 miles that are on the engine things are in pretty good shape. Again, I'm hoping it was the lack of air filter that caused the engine to break down... seems a little far fetched

Also, I'm not sure where all the black, tar-like goo that was all over the engine block came from. Could I have some problem inside my crankcase?

My muffler had a dent in it the probably restricted half the flow. Could some extra backpressure stress the head and base gaskets?

Ugh... more questions. Thanks for the info, Hondaman!

hondaman · Post by **hondaman** » Thu Sep 06, 2007 2:15 am

I would fix or replace that muffler. 2 stroke engines are much dirtier burning engines than a 4 stroke engine simply because gas and oil are being burned at the same time. This is needed to lubricate the interior parts of the engine. A restricted muffler will cause carbon buildup in the engine which is not a good thing. Make sure that cylinder is really clean. Scrape off any carbon from top of piston as well and just generally clean things up before you put the new rings on. Clean up the exhaust port as well before you put a new or repaired muffler back on.

hondaman · Post by **hondaman** » Thu Sep 06, 2007 2:18 am

Oh yea and only use 2 stroke Injector oil. Drain out whatever oil is in the reservoir if you are not sure what is in there. Using 2 Cycle oil is not good. Most scooter shops will carry the correct type of oil.

tru72 · Post by **tru72** » Thu Sep 06, 2007 4:44 am

for breaking in i always use crappy 2 stroke oil, non synthetic..
if your using the injector, i would suggest first to zip tie it open, and add a few caps of oil directly into the gas tank, mix well. Breaking in always runs way hotter than usually running temps. As for the zip tie trick..remember when you are ful throttle the engine is getting oil from the vacuum, once you let off the gas, your oil amount is significantly reduced. That tends to kill alot of injector style mixers. Do that honda man said about the breaking.. try not to put any load on it if possible..
good luck!
aloha
D

wikked_spree57 · Post by **wikked_spree57** » Fri Sep 07, 2007 2:10 am

I got some good info from this post. I just ordered a piston and rings from cheapcycleparts.com, after my disaster with my injector getting air in it, I scarred the * out of my cylinder, cracked my pison in 3 places, and broke off all the ears and that s*** is no fun to clean out of the crank case! Any tips from you guys on getting this thing back together? This is my first time ever re-assembling an engine of any kind, so I could use some help as I invested alot of money in those parts. I'd hate to spend hours working on it only to have it blow up the first time I ride it! Thanks guys, and this forum has been pretty helpful.

hondaman · Post by **hondaman** » Fri Sep 07, 2007 11:59 am

Go to the technical documents section in this forum. Click on How to install piston rings. It has pictures that may be helpful to you.

Borsch · Post by **Borsch** » Fri Sep 07, 2007 4:44 pm

I know how to do all the work, I was mostly curious about breaking in the engine and whether or not you guys think the dented muffler and lack of air filter was the primary culprit in destroying the engine gaskets. Thanks for all the info though! This site has great forums with a lot of good contribution. Hopefully when my honda dealer finally gets me my parts the spree will be running well; i'm sure that if it isn't you will hear me *' in the forums again!

Rock on fellow spree enthusiasts!

hondaman · Post by **hondaman** » Sat Sep 08, 2007 12:00 am

Yes to both of your last questions. The restricted muffler and lack of an air filter definitely did not help your engine at all.