Possible Engine Seizure - REBUILD THREAD: *HELP!!*
- Thread starter JohnnySomersett
- Start date
JohnnySomersett
Active Member
JohnnySomersett
Active Member
Re: Possible Engine Seizure - REBUILD THREAD
I thought as much, didn't look fine to me. Its from the RH cylinder. when I bought the bike, the first thing I did was put new NGKs in (the correct size), but judging by the carbon over the damage, this happened a fair while ago.
Looks like Ill need new pistons too. Oh well.
I'll be checking all of them in the week when my spring clamp arrives.
mlinder said:
I thought as much, didn't look fine to me. Its from the RH cylinder. when I bought the bike, the first thing I did was put new NGKs in (the correct size), but judging by the carbon over the damage, this happened a fair while ago.
Looks like Ill need new pistons too. Oh well.
mlinder said:
I'll be checking all of them in the week when my spring clamp arrives.
JohnnySomersett
Active Member
Re: Possible Engine Seizure - REBUILD THREAD
Would these fit (with a re-bore)?
http://www.ebay.co.uk/itm/HONDA-CB250-CB-250-G5-NOS-PATTERN-PISTON-AND-RINGS-1-00-O-S-/330996847974?pt=UK_Motorcycle_Parts_13&hash=item4d10f31566
**EDIT: Just managed to find they're the same part number for G5 or K3 so all good.
Would these fit (with a re-bore)?
http://www.ebay.co.uk/itm/HONDA-CB250-CB-250-G5-NOS-PATTERN-PISTON-AND-RINGS-1-00-O-S-/330996847974?pt=UK_Motorcycle_Parts_13&hash=item4d10f31566
**EDIT: Just managed to find they're the same part number for G5 or K3 so all good.
JohnnySomersett
Active Member
Re: Possible Engine Seizure - REBUILD THREAD
Thanks dude... and thanks for your patience with all this.
mlinder said:
Thanks dude... and thanks for your patience with all this.
JohnnySomersett
Active Member
Re: Possible Engine Seizure - REBUILD THREAD
Had another couple of hours on it tonight when I came in thanks to the lady of the house being out. Quite productive, got the cam assembly apart and out, and got all the old gaskets fully scraped off and cleaned back.
Also started cleaning up the valve area, bit of elbow grease and a stiff brush. There is some minor damage to the dome where the valves are that is very similar to the damage on the knackered piston - so definitely someone dropped something in there at some point in its life. Fortunately, its much more minor than the piston damage so once the valve compressor arrives and I can remove the valves, I am going to take a dremel and smooth it out a little bit, just for piece of mind.
I also ordered all the parts I know to need so far, come to a pretty penny too. But, its still cheaper than paying someone to fix it - or even buy a new engine!
Just waiting now, parts are gonna be arriving sometime mid next week.
Can anyone recommend any good household solutions to cleaning & rejuvenating the cases and heads etc? Cillit Bang? hahaha
Had another couple of hours on it tonight when I came in thanks to the lady of the house being out. Quite productive, got the cam assembly apart and out, and got all the old gaskets fully scraped off and cleaned back.
Also started cleaning up the valve area, bit of elbow grease and a stiff brush. There is some minor damage to the dome where the valves are that is very similar to the damage on the knackered piston - so definitely someone dropped something in there at some point in its life. Fortunately, its much more minor than the piston damage so once the valve compressor arrives and I can remove the valves, I am going to take a dremel and smooth it out a little bit, just for piece of mind.
I also ordered all the parts I know to need so far, come to a pretty penny too. But, its still cheaper than paying someone to fix it - or even buy a new engine!
Just waiting now, parts are gonna be arriving sometime mid next week.
Can anyone recommend any good household solutions to cleaning & rejuvenating the cases and heads etc? Cillit Bang? hahaha
JohnnySomersett
Active Member
Re: Possible Engine Seizure - REBUILD THREAD
I had a few things turn up over the last few days so I got to do a bit more here. The stuff that arrived was a valve spring compressor, a lapping handle and some grinding paste.... So I did the head today.
The valves came out nice and easy but were pretty rough:
BUT, I checked them all and they all seem straight - which is a bonus!
So I clamped a drill to the bench, wrapped up the ends of the valves, and got to them with various grades of emery paper, lubed with oil:
I used 60, 80, 120, 600 then 1200 grades so they are now silky smooth 8)
Then, I lapped them into the head. The paste I got had a coarse and fine paste at either end of the tub and, for my first time, it went very smoothly. I watched a couple of videos on YouTube first so I knew what to do. So here they are reinstalled:
Quite pleased how it all went
So, Im still waiting for all the parts to turn up from David Silver Spares, but, the jugs are away with the new +1.00 pistons at the local shop getting rebored, and should hopefully be done by Monday. Also, i managed to find some new engine bolts at Inox so I dont have to go hunting to replace them all at the local fixings shop.
So my to-do list now stands at:
Pull valves, check straight, de-coke and lapp into head.
Clean out crankcase of old oil and metal shavings
Get cases, head and side covers cleaned up - possibly blasted can't afford blasting, I'm just gonna wipe down
Change all oil seals
Fit new cam chain and tensioner
De-coke pistons and fit new rings - Gone with brand new pistons & rings
Need someone to helicoil one bolt in the RH cover (oil filter hatch) as one removal went a bit wrong Sorted (for free)
Get down to the local fixings shop and get a load of replacement case bolts & screws
Reassemble and install into bike!
I had a few things turn up over the last few days so I got to do a bit more here. The stuff that arrived was a valve spring compressor, a lapping handle and some grinding paste.... So I did the head today.
The valves came out nice and easy but were pretty rough:
BUT, I checked them all and they all seem straight - which is a bonus!
So I clamped a drill to the bench, wrapped up the ends of the valves, and got to them with various grades of emery paper, lubed with oil:
I used 60, 80, 120, 600 then 1200 grades so they are now silky smooth 8)
Then, I lapped them into the head. The paste I got had a coarse and fine paste at either end of the tub and, for my first time, it went very smoothly. I watched a couple of videos on YouTube first so I knew what to do. So here they are reinstalled:
Quite pleased how it all went
So, Im still waiting for all the parts to turn up from David Silver Spares, but, the jugs are away with the new +1.00 pistons at the local shop getting rebored, and should hopefully be done by Monday. Also, i managed to find some new engine bolts at Inox so I dont have to go hunting to replace them all at the local fixings shop.
So my to-do list now stands at:
Clean out crankcase of old oil and metal shavings
Change all oil seals
Fit new cam chain and tensioner
Reassemble and install into bike!
JohnnySomersett
Active Member
Re: Possible Engine Seizure - REBUILD THREAD: *Head work done*
I couldn't find it! I did find people talking about having to cut metal out of the engine to get it to fit though which made me dubious as to whether I wanted to do that. I have already ordered a replacement stock unit... I figure if the original lasted that long then I trust a new one to be fine.
mlinder said:
I couldn't find it! I did find people talking about having to cut metal out of the engine to get it to fit though which made me dubious as to whether I wanted to do that. I have already ordered a replacement stock unit... I figure if the original lasted that long then I trust a new one to be fine.
JohnnySomersett
Active Member
Re: Possible Engine Seizure - REBUILD THREAD: *Head work done*
I didn't, no, but I will now you mention it. I've got some white spirit that'll do the job.
teazer said:
I didn't, no, but I will now you mention it. I've got some white spirit that'll do the job.
JohnnySomersett
Active Member
Re: Possible Engine Seizure - REBUILD THREAD: *Head work done*
Glad I checked...one exhaust valve was letting by a bit. Soon ground that out though and now its tighter than a nuns ass!
Box of parts shipped today so should be with me soon, all bar one part (rotor bolt) that's following in a few days, but that means I can start getting this thing back together.
teazer said:
Glad I checked...one exhaust valve was letting by a bit. Soon ground that out though and now its tighter than a nuns ass!
Box of parts shipped today so should be with me soon, all bar one part (rotor bolt) that's following in a few days, but that means I can start getting this thing back together.
JohnnySomersett
Active Member
Re: Possible Engine Seizure - REBUILD THREAD: *Head work done*
Pretty much all the parts arrived yesterday so I got to work putting it all back together. I managed to get the bottom end in place and the RH side with the clutch and oil filter sorted.
Quick question though, the pistons.... Do they go in with the diamonds on the crown facing toward the back or the front of the engine? That's my job tonight and I'm not sure which way they should go!
Pretty much all the parts arrived yesterday so I got to work putting it all back together. I managed to get the bottom end in place and the RH side with the clutch and oil filter sorted.
Quick question though, the pistons.... Do they go in with the diamonds on the crown facing toward the back or the front of the engine? That's my job tonight and I'm not sure which way they should go!
JohnnySomersett
Active Member
Re: Possible Engine Seizure - REBUILD THREAD: *Going back together*
So far, so good. Yesterday I got the pistons and cylinders in, then the valves and now I'm working on the camshaft end.
I have run into a bit of an issue, hopefully you guys can help....
I put it all together as per the manual: Rotor on the LT mark, cam sprocket with the cutout/L level with the top of the camcase, and installed the 2 cam sprocket bolts as directed (you can see the 'shoulder' relief in the camshaft thread.
BUT, at that setting, the left exhaust valve is at full open when the left piston is at TDC (LT mark) and actually touches the piston!
I can't seem to fathom out how I can get this not to happen! Ive just spent 2 hours trying, and read both manuals' sections on this and I still cant get it to play ball!
Also, the chain seems awfully tight (no tensioner installed yet)....is this normal!?
HELP!?!?
So far, so good. Yesterday I got the pistons and cylinders in, then the valves and now I'm working on the camshaft end.
I have run into a bit of an issue, hopefully you guys can help....
I put it all together as per the manual: Rotor on the LT mark, cam sprocket with the cutout/L level with the top of the camcase, and installed the 2 cam sprocket bolts as directed (you can see the 'shoulder' relief in the camshaft thread.
BUT, at that setting, the left exhaust valve is at full open when the left piston is at TDC (LT mark) and actually touches the piston!
I can't seem to fathom out how I can get this not to happen! Ive just spent 2 hours trying, and read both manuals' sections on this and I still cant get it to play ball!
Also, the chain seems awfully tight (no tensioner installed yet)....is this normal!?
HELP!?!?
