Topic: 75' CB750 hardtail

[valt]

Alright so I have finally broken down and decided to make a thread about my hardtail project. Basically I bought a rough running 75' CB750 K5, that had a title. I then went to TC Brothers and got a hard tail and electronics and battery boxes. Had the hard tail welded on by a local welder here in town, threw the motor back in it and got it running. That's where I'm at currently, but here is a little back story.

When I got the bike, it had a really bad head gasket leak. I tore the top end down and found this



So basically a completely ruined head gasket, I then proceeded to replace all the gaskets in the top end. Including the base gasket, and all o rings. Now the issue I'm having is that it is DUMPING oil out of either the 2 or 4 cylinder exhaust. I'm pretty positive that its #4, since there is a fair amount of smoke coming from that exhaust port. Before I took the bike apart it had some mild smoke, but it definitely wasn't dumping oil like it is now.

So my question is what could be going on here? I don't think that the rings are that bad, and we definitely didn't break any putting it back together. I haven't run a compression test yet, but if I find bad compression that could be several things. I'm just confused what could be going on here, since the amount of oil coming out of the pipes is pretty large. I don't know how it actually runs like that.

Alright well if anyone has any ideas what it could be I would appreciate it. Also here is a video of it running, you can see how smokey it is here.

! Video not found

edit for more pictures!

[A Grove]

Looks great!1 I'm jealous, as this is exactly what I want to do, only with my 550.

[what huh]

ive been looking for someone who was doing this to a 750. And found a lot but they werent the exact look i was going for and if you keep going the way it looks like you are going, it will be what i have been invisioning for awhile now.

Im really looking forward to progress on this

[valt]

ive been looking for someone who was doing this to a 750. And found a lot but they werent the exact look i was going for and if you keep going the way it looks like you are going, it will be what i have been invisioning for awhile now.

Im really looking forward to progress on this

Well as far as stuff going on the bike there isn't much else. It's going to get headlight, tailight/liscense plate assembly, and forward controls. The frame and rims will be powder coated black and side covers and hubs polished. These tires will be going on it and then grips and thats it.



Oh it will have a springer seat and no fenders as well.

[A Grove]

Can you tell me what brand/model those tires are?  I see them everywhere but havent a clue...

[valt]

Can you tell me what brand/model those tires are?  I see them everywhere but havent a clue...

They are these right here

http://store.coker.com/450-18-firestone-deluxe-champion-blackwall-tire.html

[greenjeans]

I shoved some of those on my '72.  With black rims & they look great.   4.5 x 18 rear  4 x 19 front.  They handle like truck tires....but they sure look cool
Can't wait to see this one finished.   Has a great look already.  Amazing what a rigid frame does to these

[what huh]

Oh it will have a springer seat and no fenders as well.

thats all i wanted to hear i cant wait until its completly done

[what huh]

could you post a picture from the side? 

[fuzzybutt]

that decides it for me. i'm going to do a hardtail 750 with that weld on kit from tc bros

[valt]

could you post a picture from the side? 

Sure here is a picture of the rolling frame without the motor as well as just the frame itself.

[rachet]

I'm loving how this is shaping up and just want to tag it so I can follow along.

Rach~

[DaytonGuy]

That looks like the TC Bros. bolt on/weld on hard tail.  they don't make one of those for a 550...I've asked.  They claim they are working on one and may have it by fall.  If one were to buy the weld together hardtail kit they sell, would one need take it to a bike shop to have it installed or could a good local welder do it?  How much do you think it would cost to have done?

[rachet]

Hey Valt,

Maybe you could take some close up pics?  That way DaytonGuy could see what he's up against.  I would think any reasonable welder could handle the job.

Rach~

[valt]

Hey Valt,

Maybe you could take some close up pics?  That way DaytonGuy could see what he's up against.  I would think any reasonable welder could handle the job.

Rach~

Sure thing, I have a couple close ups of the top piece. Yes any welder could do it, I just had a local guy do it for me. He charged me about $120.00 to do it, so not very much at all. TC Brothers supply a instruction sheet with the hard tail that show you how it goes on as well. I will try and get some close ups of the lower welds today, but really any welder could do this.

[rachet]

Not to criticize, but it doesn't seem exactly square... The right side seems a little pulled back.  Is it just the brace?

[valt]

Not to criticize, but it doesn't seem exactly square... The right side seems a little pulled back.  Is it just the brace?

When you cut the frame it has a tendency to shift a little. Also the hard tail could very well have not been completely straight. The welder lined everything up and the frame is straight, it just looks funky.

[rachet]

That's good to know.  I would hate for you to only be able to turn left! 

It looks great in all the other photos!

Did you cut the frame yourself, then haul  it over to the welders?  I would think if someone was planning to do this,it would be best to cut and weld at the same time, to prevent "tweakage".

[valt]

That's good to know.  I would hate for you to only be able to turn left! 

It looks great in all the other photos!

Did you cut the frame yourself, then haul  it over to the welders?  I would think if someone was planning to do this,it would be best to cut and weld at the same time, to prevent "tweakage".

I had the welder cut the frame, since he was doing the welding I figured it would be easiest for him.

[valt]

Well crap, I pulled the plugs and found 2, 3, and 4 covered in oil. The plug on 4 was just wet with oil and looked like it had been barely firing. The strange thing is that #1 looks really rich but no oil that I could see.

Anyone have any idea what could be going on here? I'm going to tear it down again this weekend and see what I can find, but I'm not really sure what would cause this. It absolutely does not leak on the outside at all though, and to the best of my knowledge it did not blow oil before I took it apart.

[A Grove]

Leaky rings?

[DaytonGuy]

I think your bike looks pretty sweet so far.  Can't wait to watch the progress.

The issue I'm dealing with is this.....

That hardtail, is allready assembled by TC Brothers and I believe it bolts onto the frame where the swing arm used to attached with some welds to add additional support.  It then welds up to the top of the frame as your picture shows.

For a 550, the only thing I can find is a kit that has to be completely welded together.  They come as 4 pieces of bent tubing with some cross braces and axle plates etc.  I don't weld, so I'm trying to decide if I want to buy one for my bike, and if so, who would I look for to weld it up?  Would your run of the mill metal shop guy know how to align it up or do I need someone with motorcycle experience.

I apologize if I appear to be highjacking this thread....that was not my intent.

[valt]

I think your bike looks pretty sweet so far.  Can't wait to watch the progress.

The issue I'm dealing with is this.....

That hardtail, is allready assembled by TC Brothers and I believe it bolts onto the frame where the swing arm used to attached with some welds to add additional support.  It then welds up to the top of the frame as your picture shows.

For a 550, the only thing I can find is a kit that has to be completely welded together.  They come as 4 pieces of bent tubing with some cross braces and axle plates etc.  I don't weld, so I'm trying to decide if I want to buy one for my bike, and if so, who would I look for to weld it up?  Would your run of the mill metal shop guy know how to align it up or do I need someone with motorcycle experience.

I apologize if I appear to be highjacking this thread....that was not my intent.

It's fine, I'm happy to be helpful when possible. I have a 74' CB550 as well, but it is stock but terribly different from the 750 frame in the back. You should be able to find weld on hard tails for 550s, and as for a welder. I'm sure any competent welder would have no problems welding a hard tail on. The guy I went said he had done several CB750s, and I would imagine that where ever you are you can find someone who has done one before. Putting hard tails on frames is not exactly a rare thing for people to do, just ask around your area I'm sure you can find someone easily.

[A Grove]

I would want to be there when he's aligning it all together, though.  But beyond that, any welding show/welder with a good reputation can handle welding these frames.  Not a BIG deal with the thick walled tubing, etc.

EDIT:: I'll try and start a build thread for my almost-finished 550 hardtail frame.  I bent/made the ass-end myself, its coming along nicely.

[devbear12]

QUICK NOTE:  when cutting these frames apart try to temporarily weld braces across the frame to keep it square then after cutting and welding (cause welding heat causes missalignment) take the braces off>>>>>>  sure would suck to have all that work and your engine mounts not fit right.