superdream top end rebuild

[Ant132]

Here are some pics of the top end of my superdream. It didnt seize or break down or anything, im just rebuilding it as i have the week off and the head gasket was leaking and it burns oil .

http://i101.photobucket.com/albums/m62/ant-147/DSC000148.jpg

http://i101.photobucket.com/albums/m62/ant-147/DSC000157.jpg

http://i101.photobucket.com/albums/m62/ant-147/DSC000167.jpg

http://i101.photobucket.com/albums/m62/ant-147/DSC000176.jpg

http://i101.photobucket.com/albums/m62/ant-147/DSC000186.jpg

http://i101.photobucket.com/albums/m62/ant-147/DSC000195.jpg

This being the first 4-stroke ive owned/worked on i havent got a clue if the above pics tell me anything substantial. Am i missing anything obvious or does it all look fine?

My plan is fit a new top-end gasket set and new piston rings all round. What should i be doing with the valves? I was planning on just cleaning everything, getting the excess carbon off and and re-assembling.

Just wondering if im missing anything obvious or any recommendations on what to do or check before i re-assemble?

One thing i noticed is the RH piston is slightly wet with oil whereas the LH piston was dry. Im wondering if this is linked to the fact that when the bike is really warmed up it smokes slightly from the RH exhaust when idling or pulling away.

Cheers for any help, Ant

[rosszx9r]

Here are some pics of the top end of my superdream. It didnt seize or break down or anything, im just rebuilding it as i have the week off and the head gasket was leaking and it burns oil .

Just wondering if im missing anything obvious or any recommendations on what to do or check before i re-assemble?

well you've done the hardest part and got the top end off. you might as well well get the engine rebored with new pistons (IMHO

at the very least, new piston rings like you say. the valves need lapping in once you've cleaned them up. you will also need new valve stem seals. you can usually buy a top end seal kit with all the parts you need for this. shouldn't be too expensive.

with all this done, you should see a big improvement in throttle response (well, as much as you can expect from a superdream ) and it should sort out the oil burning issue too...

[Ant132]

Thats just what i wanted to hear mate, thanks alot for your help. In an ideal world i would replace the barrell, pistons and rings, get the valve seats recut etc. but i simply cant afford it. but saying that ive gone this far so may aswell do a proper job.

Im going to hope for the best and measure everything for service limits and if my luck is in she will be happy with new rings. If not it might have to wait a bit longer for a rebore and new pistons. Ive seen on the halfords website that there is a valve grinding tool, im hoping that will do the job if the seats are ok.

Yeah throttle response was quite poor and felt lumpy at low revs, it wouldnt idle smootly either and i think that was the HG. When i took the head off it came off really easy, easier than i expected as from what the manual made out i would have to hit it with a hammer. I never, it came off in my hands (dont know wether thats good or bad ) the head gasket was a mess and explained the oil leakage around the fins in an instant.

thanks again mate, Ant

[rosszx9r]

In an ideal world i would replace the barrell, pistons and rings, get the valve seats recut etc. but i simply cant afford it. but saying that ive gone this far so may aswell do a proper job.

no need to replace the barrels

rebores aren't that expensive. get a quote from a bike shop before discounting it!

the tool for the valve seats should be a stick with a sucker on the end. you put a little grinding paste on the valve seats then use the stick like you're trying to start a fire by rubbing it between your hands... not easy to explain but what i'm trying to get at is it's easy and cheap to do. don't go spending money on fancy drill attachments of fancy tools!

sounds like the head wasn't tight enough so you'd of lost compression possibly. you would need a micrometer to measure the barrels properly. if you take it to a bike shop (a proper one! not a nessesarily a dealer) they should be able to measure it for you.

if your looking to keep the cost down to a minimum, new rings will make a difference. with a top end overhaul and new gaskets and the valves reseated, you probably will get a decent running bike. remember to run it in properly too for at least 200 miles

if you've not got a manual, i can scan the relevent sections out of my old haynes for you or you can google valve seating. probably find a youtube video on this too if you take a look!

[Ant132]

Thanks Ross,

I think i might have been overestimating the cost of a rebore then because a cb400n barrel from david silver is only £50 so though it would have been cheaper and easier for the new barrel.

Went to halfords earlier and bought the valve grinding tool as you explained, going to attempt them all tomorrow.

Also finally found a place that stocks new rings so i can crack on with ordering them now Thanks again, ant.

[rosszx9r]

a cb400n barrel from david silver is only £50 so though it would have been cheaper and easier for the new barrel.

just be careful with changing barrels.... the piston still needs to match the barrel size!

you can buy pistons in a number of oversizes. the superdream has 4 piston sizes so it depends how worn the barrels are as to which one you need. david silver might be offering refurbed ones so check the piston size before you order as you'll be needing new pistons anyway if it doesn't match the ones you have. btw - piston diamater should be 70.47 - 70.49mm oversizes come in 0.25mm increments.

[Ant132]

Thanks Ross, i measured the pistons on a vernier gauge ealier and they are the tiniest bit under 70.5mm so im certain they are standard. Im going to order the rings tomorrow, the barrel and pistons are real good condition actually, im not going to replace as they are all within the limits luckily enough.

[Guest]

In an ideal world i would replace the barrell, pistons and rings, get the valve seats recut etc. but i simply cant afford it. but saying that ive gone this far so may aswell do a proper job.

no need to replace the barrels

rebores aren't that expensive. get a quote from a bike shop before discounting it!

the tool for the valve seats should be a stick with a sucker on the end. you put a little grinding paste on the valve seats then use the stick like you're trying to start a fire by rubbing it between your hands... not easy to explain but what i'm trying to get at is it's easy and cheap to do. don't go spending money on fancy drill attachments of fancy tools!

sounds like the head wasn't tight enough so you'd of lost compression possibly. you would need a micrometer to measure the barrels properly. if you take it to a bike shop (a proper one! not a nessesarily a dealer) they should be able to measure it for you.

if your looking to keep the cost down to a minimum, new rings will make a difference. with a top end overhaul and new gaskets and the valves reseated, you probably will get a decent running bike. remember to run it in properly too for at least 200 miles

if you've not got a manual, i can scan the relevent sections out of my old haynes for you or you can google valve seating. probably find a youtube video on this too if you take a look!

see here its much the same

https://cid-9e0ddcb0b813d946.skydrive.l ... z/2.27.jpg