Project CB250T (AKA Project Blimp)

**Bonez** · 20th November 2004, 16:52

Ok it's a poggy ol Japper 250 (around 400lbs) that's been out in the weather neglected for the last two years. These models had a 3 valve head, semi automatic camchain tensioner and counter balance chain adjuster (both of which usually got neglected by owners and/or mechanics who thought they where "automatically" adjusted. This things camchain guide is slopping around in the head like a cock in a sock so I'm guessing the tensioner has either seized or was never correctly adjusted. Either that or the locating pin has come adrift/seperated from the guide assy. Was surprised it actually ran. Having only payed $NZ100 I'm happy to tinker with it and have set a budget which I will not exceed (well at least the next 6 months anyway

) I may in the end to just wreck it but at the mo I'm enjoying getting down and dirty. Some I'll say it's not worth it but I haven't pulled a bike engine completely to bits since about the late '80s when I did up the '76 CB550F engine. The 250 engine doesn't smoke which is a good indication the bore/head/rings etc are in good nick. You'll see pickies in the "Bugger" thread, some of which I'll transfer here. Seat pans buggered but I see David Silver spares in the UK has complete seats at a reasonable cost wonder if Econohonda have any?. I've removed the carbs with the aid of vicegrips on a couple of manifold attachment bolts in head. Am using ATF fluid as a penetrating oil (Hey for $5 for one litre at K-Mart why not

. The LH muffler off (degorge around 8ozs of contents onto the garage floor), RH muffler very shortly and the header studs removed complete because the nuts where completely seized to them. Was surprised to see the exhaust collector box wasn't completely rusted through. I have no idea of it's millage as the instruments where missing. The LH case looks like a chain has let loose sometime in its past. Will be getting an air compressor shortingly for "house maintenance" but.......Any donations/contributions in the way parts/constructive advice to this project would be greatfully received.

**Bonez** · 28th December 2004, 08:26

Finally got around to having a play. Removed the LHS cylinder rockers and low and behold the exhaust rocker bearing surface is worn right down to the rocker arm. no wonder the engine was noisy. The intake one has started to go. No issues on the RHS one's at all. Surprisingly there's no disernable wear on the cam lobes to worry about. If anyones got a wrecked 250/400/T/N loafing about in the Palmerston North area i'd be interested in bits n pieces.

**DEATH_INC.** · 29th December 2004, 18:15

My mate up here has some bits,should have some rocker arms......lemme know if you can't get any down there......

**FROSTY:Me** · 29th December 2004, 18:37

Originally Posted by Bonez

Finally got around to having a play. Removed the LHS cylinder rockers and low and behold the exhaust rocker bearing surface is worn right down to the rocker arm. no wonder the engine was noisy. The intake one has started to go. No issues on the RHS one's at all. Surprisingly there's no disernable wear on the cam lobes to worry about. If anyones got a wrecked 250/400/T/N loafing about in the Palmerston North area i'd be interested in bits n pieces.

Just a thought dude--why not get the arms built up and reground?

**Bonez** · 29th December 2004, 18:42

Originally Posted by XJ/FROSTY

Just a thought dude--why not get the arms built up and reground?

Was talking about that with a mate yesterday. Will do it if non turn up. Thanks for the input guys.

**Kickaha** · 29th December 2004, 20:46

Originally Posted by Bonez

Was talking about that with a mate yesterday. Will do it if non turn up. Thanks for the input guys.

Just had some done by Kelford cams in Chch and it cost $20-$30 each depending on how bad they were.

**Bonez** · 30th December 2004, 07:41

Originally Posted by Kickaha

Just had some done by Kelford cams in Chch and it cost $20-$30 each depending on how bad they were.

Info added to my hot gen list. Thanks.

**Bonez** · 4th January 2005, 10:38

Removed the buckled and rusted front mudguard. Angle ground the the rivets fender of the mount off and put the mounting bracket aside for futher use. The Rh muffler and both headers were rusted in position on the collector box so with a bit of giggerpokery managed to remove it from the bike. Will have to get hold of a heat source so I can seperate them without damage too much effort. As you can see there's no real hurry. Just enjoying the tinkering. Would much rather be out riding. Playing with it reminded me why I prefer working on old m/cs to cars. Spending a few hours trying to sort out a steps-son's Pajaro enforced this too. Had to improvise on that thing and use part of a C50 tire tube

.

**Bonez** · 4th January 2005, 13:57

Got the muffler off with the help of a vice and big hammer

. Will leave the header in one peice as they will be painted the same colour anyway.

Remembered I had a cb250rs seat and tail peice and bikini fairing around somewhere so have decided these will go on. Cut the front of the seat pan. Just need to find the staple gun to pull the vinyl in. The RS seat is plastic not like the Ts one, which is steal, so no rusting issues. Had to cut the seat retaining clips off the frame so the RS seat would come down to the bottem edge of the tail peice fitted over the top edge of the frame.

Have cut the grab rail to allow the tailpeice to fit also. Fitted them to the frame upside down. There is enough room on the end of them to attach indicators and a rubber cap will be fitted. Now to make some brackets to secure the seat.

Took the rear wheel off and managed to unseize the drum break spindle with the aid of WD40 and the vice. Drilled two holes up though the upper front edge of plastic mudguard which is part of the airbox. with a 12mm drill. This gives me access to existing holes either side of the frame where I can mount the seat to. Rubber bungs will be fitted to prevent crap getting up there once the seat is secured.

Removed the rather huge air box and waterblasted the rear of the frame,stands and tyres(these had moss in the treads). I'm surprised there is no sign of tire rot. There isn't much wear on them, so I guess they were put on not long before it was parked up.

**Bonez** · 17th January 2005, 05:54

Just managed to purchase a Haynes w/s manual for it off Trademe for under $10 including postage.

**Bonez** · 5th March 2005, 19:53

Have decided to scrap it. Will get my dosh back in scrap ali and tyres. Went to watch the racing at Manfeild, step son James (jimbo to his mates) only to be told my "japper" wasn't allowed in the gate-tossers. So vented my anger on the 250

.

**moko** · 6th March 2005, 01:19

Bit of a shame bonez,the follow-up model was the CB250N which Honda gave the truly awful name of Superdream.Shit name or not they sold huge numbers of them and there are still quite a few about,I`ve had 4 250`s and 2 400s over the years.The 400 is actually a very tidy bike,I reckon it would still give a GS500 a run for it`s money if they still made them.Last i heard they were being built in Malaysia or somewhere under licence.

**Combattant de Rue** · 6th March 2005, 02:27

Originally Posted by Bonez

Have decided to scrap it. Will get my dosh back in scrap ali and tyres. Went to watch the racing at Manfeild, step son James (jimbo to his mates) only to be told my "japper" wasn't allowed in the gate-tossers. So vented my anger on the 250

.

What a shame. I was enjoying reading your progress. Do you plan on starting another project Bonez? I can donate a (GPX) 2cylinder 250 4 stroker from my collection of kawasakas.

**inlinefour** · 6th March 2005, 07:24

Then give me a holler as I believe that I might have a few good CB400T parts and I would be surprised if they are not interchangable.

**Bonez** · 6th March 2005, 15:21

Originally Posted by moko

Bit of a shame bonez,the follow-up model was the CB250N which Honda gave the truly awful name of Superdream.Shit name or not they sold huge numbers of them and there are still quite a few about,I`ve had 4 250`s and 2 400s over the years.The 400 is actually a very tidy bike,I reckon it would still give a GS500 a run for it`s money if they still made them.Last i heard they were being built in Malaysia or somewhere under licence.

I think there was a pom CB450 model and of the 450 "Rebel" motor was a continuation of the line I think. I do like the GS500s though-simple.