Conkers Swedish Cafe racer Project.

yes it is normal. the tab is there to make sure the dowel pin does not back out.

conkers said:

Next Question Gurus!

About the split the crank, noticed that only the "bottom" pair of bolts have a tab washer and the "top" pair of bolts seem a little short for the nuts.

Is this normal?

Click to expand...

Thanks....
And when I was loosening the nuts I figured out why the two top (outer) ones are deeper... so the wrench can locate!

I then spen an hour dlowly polishing the inner bore or the oil pressure relief valve to be able to get the plunger out snd clean the valve internally......

I can't believe I consisered just filling with oil and trying to start this engine.... everything is claggy and dirty....

I'll have a go at the oil pump next I think.

Conkers

Since you're starting with the Combat motor you have the option of staying with it and its features or adjusting it.
I started with a Combat and since I was going to restore from crank up I considered all the options.

The Combat motor is optimized for performance that really doesn't kick in until the 6,000 range and with the 19 tooth trans sprocket is best blasting stop light to stop light. Others I'm sure will disagree.
If that is what you are after then by all means stay with the Combat configuration.

I however wanted a bike that was more tractable in town and would give me good performance without having to wring its tail.
I detuned mine and am extremely happy with it and when I want to really go it pulls like a train.

What I did was:
Spacer under barrel from OldBritts to lower compression of Combat (10/1) closer to standard (9/1) Less chance of pinging.
Put in new standard cam in place of 2S Combat.
Put on single 34 mm Mikuni VM. Easy starting, durable and easy to tune. Single carb manifold.
Pazon Sure Fire electronic ignition.
Oil filter setup, OldBritts
Reed type breather. Mikes SX650. Works great and cheap.
21 tooth gearbox sprocket.
Podtronics (OldBritts) replacement for Zener Diode (failed) and Rectifier. (Easy and cheap)
Iridium plugs.

Starts 1-3 kicks, idles nice and really scoots when wanted.

Replacing Layshaft bearing in gearbox strongly recommended. Lots of threads on subject on why and how. Can be done in bike.
All of this has to do with how you plan to ride the bike but at 63 I'm not looking to prove I'm the hottest rocket in town.

Keep posting progress with pictures.
Good luck.

Bob

You mentioned that you planned to replace guides.
There was a thread a short while ago on the subject and you will want to review it.
Big issue of heating head for removal and installation of guides.
You may want to confirm your replacement guide OD since oversize ones available and if standard OD may not ultimately be a tight fit.
Bob

Hi Bob,

thanks for the advice.

I am not worried about the head and guides, they are under control. I have been modifying heads professionally since 1985, whilst I would not presume to know everything, I am confident that the head/guides/valves are the least of my worries. The good thing is that working in the engine tuning branch I have good contacts for machining work that I can't do myself.

Good tip about lowering the compression and going for a softer cam, I doubt I will spend much time above 6000rpm.... but I would like to experience the combat buzz... I might detune it on the next rebuild though...... or tune it up if I decide to go racing!

But it's a long way off, and the spec that you are running sounds like something I would like.

Thanks...

Mike

ps. Apologies in advance for a Non Norton picture.. but here is one of the heads I developed and tuned for Per Eklunds Pikes Peak Winning 850bhp 2000cc SAAB. ;-)

I am NOT a fan of the spacer plate under the cylinder as you now have 2 surfaces to seal and can cause the cylinder to move about along with more difficulty to keep it tight. I much more prefer to machine the piston tops .020 to max .030 to lower the compression. with .020 off the tops and the combat cam it will still perform quit well on today's high test fuel.

conkers said:

Hi Bob,

thanks for the advice.



Good tip about lowering the compression and going for a softer cam, I doubt I will spend much time above 6000rpm.... but I would like to experience the combat buzz... I might detune it on the next rebuild though...... or tune it up if I decide to go racing!

But it's a long way off, and the spec that you are running sounds like something I would like.

Thanks...

Mike

ps. Apologies in advance for a Non Norton picture.. but here is one of the heads I developed and tuned for Per Eklunds Pikes Peak Winning 850bhp 2000cc SAAB. ;-)

Click to expand...

+1 with bill's advise on the spacer plate; to lower the compession on a Combat motor. I did just that back in the late 80s for a Combat I had at the time. It worked, but I wouldn't install one again ... for the reasons he gives. In fact, not sure if I even will use a base gasket on my next build. Just my 2 cents ...

I can see how a copper gasket / base plate under the cylinders on a 750 might be an issue, but what about an 850 motor with the through bolts? Cj

why would want to lower the compression on an 850 as they will almost run on lamp oil now????

cjandme said:

I can see how a copper gasket / base plate under the cylinders on a 750 might be an issue, but what about an 850 motor with the through bolts? Cj

Click to expand...

I wasn't really thinking of lowering the compression ratio with my post, bill, but re reading it that's why it was brought up. I was thinking of using a copper gasket because of how the others compress, however it's about a spacer and not just a gasket, soooooo......disregard. Cj

bill said:

why would want to lower the compression on an 850 as they will almost run on lamp oil now????

cjandme said:

I can see how a copper gasket / base plate under the cylinders on a 750 might be an issue, but what about an 850 motor with the through bolts? Cj

Click to expand...

Click to expand...

Lamp oil, I like that.

I believe Jim Schmidt is offering copper base gaskets.

Its been a while so I'm not sure of the base spacer I got from OldBritts but metal either Alum or Copper.
I put Gascosynch (sp) sealer both sides and tightened down. Tightened again next day before putting on head.
Its been 6,000 miles since and no leak. I do have reed valve to help though.

Even though milling top of pistons probably ok unless the 2S cam is replaced with a softer one the motor will still have to be revved pretty good to get into its power range.

Bob

I set about cleaning the surface muck and light corrosion build up/discolouration from my conrods today, also beadblasted the head and valves to inspect the condition and factory porting of my Combat head.

Polishing the rods took an age, 120 grit, scothbrite wheel and felt with metal polish and finally buffed with felt wheel and wax.
No pictures of the final sheen on the rods.
Head porting... rubbish, so I'll clean that up.
Valves looked great, until I beadblasted them to reveal the surface of the moon. New valves added to my parts list.

Crank cleaned and journals polished.























Mike