'84 1200 engine for a '82 GW

[ekvh]

Have you checked compression since advancing cams? If not, you may be surprised.

 

[slabghost]

Actually the compression isn't very much below book values and are all pretty close so I would simply ignore that. Getting the carb right and timing of ignition will give you more performance than higher compression. Look at it this way. Lower compression means easier starting.

Another thought is that cam timing is probably at it's best now. :BigGrin:

 

[canuckxxxx]

ekvh » Fri Jul 31, 2015 2:33 pm[/url]":28ff50xf]
Have you checked compression since advancing cams? If not, you may be surprised.

See post #349

 

[joedrum]

well after considering all this discussion on advancing and retarding cams and all the numbers thrown in ...im still going to stay on the timing marks of motor and at head ....no matter what ..in this possition the cam is sitting in the spot as it dose in a 1000 motor or 1100 motor ...it has to ..with two marks the same for sure makes all three motors have cam in same spot ..the only way this could be different is if the TDC mark on the crankshafts were different on the motors and i dont think they are ....the one thing for sure also is the 1200 motor travels further in its rotation path ..this creates more flow has too ..... ...seems if you play with mechanical timing as this is ..if you help compression you probably hurt flow some ..so it starts to be a self canceling move in my opinion ...not to say theres not a sweet spot seems there is always a hidden sweet spot....but i think this is more gotten with ignition timing and advance curve ....the stock ignitions you guys are dealing with or dyna ..is simply a shot in the dark that has a hard time to do what it says as in numbers lots of varibles there that makes that a joke with all the moving parts springs and inaccuratcy in there system and especially so with the cv carb set ups ... sheesh what do you think carbs go through on a backfire with cv carbs ... slides can blow apart ive seen it ....i wont go on about this huge discount in carbs and ignition ...but with a c5 ignition like hooch has ..it is like a carb really most think carbs are stone age tech ..in reality there a super tool thats really hard to beat ...you have to make a non carb for them not to work good ..that pretty much covers all carbs produced since the seventies ...a real carb can be adjusted everywhere in the rpm zone ...fine tuned with almost no moving parts and dependent on nothing but suction to work ....c5 in a iggy way can be dialed in like a real carb can perfectly ... providing fire right where your cam and motor need it ... i think my 1200 mod motor is rather close in the timing and matching the cam and motor and the carb is not bad either ... and it runs like that also with everything so non dependent on other things simplisity takes over and bike runs consistant bigtime .....

as someone with a lot of time in this 1200 mod motor i simply have to disagree with the number game as no numbers out apply to this motor and cam ..if my numbers dont match 1000 numbers so be it at TDC cam and piston are in same spot ...ill dial it in from there :fishin:

 

[canuckxxxx]

Joe, I think we should agree to disagree about the timing marks vs valve timing. I'm going to leave the valve timing where it is now.

I went for a short ride yesterday AM and the bike is running fine. :good: Getting too caught up in the numbers: compression, valve timing etc. :rtfm: time to just ride the think and enjoy it. :Egyptian: Tired of thinking about it. :head bang:

Brian

 

[joedrum]

good move .. me too ...and this is great way to wind up the thread... nothing concrete but a lot to think about ... i think maybe where you are at brian with keyway mod might be sweet spot as now were talking very small move ... id say now issues must go to other soruses now ...

 

[Denver]

Back to degree of advance of the trigger wheel, of four or six degrees in ignition to boost power without anything but better gas needed to prevent pre ignition. :doh: :hihihi:

 

[slabghost]

Trigger wheel is on 1500 motors or C5 ignition.1100 and 1200 motors use rotor.

I agree with your plan Brian Ride the thing!

 

[Ansimp]

slabghost » Mon Aug 03, 2015 6:45 am[/url]":2bkfs3op]
Trigger wheel is on 1500 motors or C5 ignition.1100 and 1200 motors use rotor.

I agree with your plan Brian Ride the thing!

+1 :moped: :good:

 

[Denver]

Agree ride it while the sun shines!!! :music: As for trigger wheels made only for 1500's, thats true, k: talked to the guy who made them, said idea sould work on 85-87's. :yes: And you could modify stock wheels on those models, in the same way, :doh: :clapping: not enough demand for him to do it. :cheeky:

 

[canuckxxxx]

I've put on about 500 miles since my last post. Got some good numbers to report:

Borrowed the neighbor's compression tester...I got 155 on all cylinders. Whereas I got 150 with my cheap Canadian Tire compression tester. I am happier believing the higher numbers so that is what I am going with. :music2:

Did a mileage test today. Went 103.8 miles and used 9.8L (2.59 USG) which works out to 40 mpg which I think is excellent. :good: Remember I got about 38 mpg when it was an 1100. So maybe the taller gearing is helping. :Egyptian:

Did a compete test of my ignition timing. :builder: Tried to do it as per the manual but wasn't feeling confident about the results. So I put my degree wheel on the front of the crank. For 1200 timing should be 10º BTDC for idle, 32º BTDC max with mechanical advance, 45º total advance including vacuum advance.

I marked those angles on my degree wheel with a felt marker so I could see them with the timing light. I got 10º BTDC for idle, 38º BTDC max with mechanical advance, 47º total advance including vacuum. This makes sense too because I took the pulse generator and advance unit off my 1100 and put it in the 1200 and the max advance with mechanical is 38º for an 1100. The 47º with vacuum is with the engine screaming. I don't know the RPMs because I was reaching up to use the throttle while looking at the degree wheel this the timing light.

I should point out that I bought a 3' piece of 1" radiator hose, put a 2' piece on the bottom engine connector and a 1' piece at the top fitting. Filled the engine up with coolant and then connected the two open ends with a piece of 5/8" heater hose which fits tightly into the 1" hose. So anyway the engine didn't overheat for the few minutes it took to check the timing.

I thank you for your indulgence.
Brian

 

[slabghost]

Really good numbers! Ride it as much as you can until the snow flies. I don't think the 1200 will need re ringed.

 

[joedrum]

nope things sound really good brian ....

 

[canuckxxxx]

slabghost » Fri Sep 18, 2015 7:42 pm[/url]":1poq65qd]
Really good numbers! Ride it as much as you can until the snow flies. I don't think the 1200 will need re ringed.

You called it right, Slabghost. Funny how that extra 5 psi makes a big difference in how you think about it.

Remember the valve timing is advance to 9º BTDC. I was thinking that was going to kill my gas mileage but what was really making it suck gas was my jetting. My Weber came with 105 primary main jet and 95 secondary main jet. When it was an 1100 the plugs were very white and I thought it was too lean so I swapped the two main jets and drilled the 95 out to 120 (which was now in the primary) and that seemed to work better for the 1100. But with that jetting on the 1200 the plugs were much darker. So I swapped the main jets back again so they are in their original positions. That made a huge difference in gas mileage.

Minor issue is that now my secondary is 120 instead of 95 which it probably should be. Will have to find one.

That trip I made to that glacier last weekend was before I changed the jetting. For some reason I thought to bring along a gas can full of gas. Good think I did because at about 110 miles the bike started missing and I had to put it on reserve :shock: . Nearest gas station was 30 miles away. I never figured out my mileage from that trip because I had added the gas can gas but I think it was really bad...less than 30 mpg.

Brian

 

[canuckxxxx]

joedrum » Fri Sep 18, 2015 8:21 pm[/url]":gckmpd5p]
nope things sound really good brian ....

Thanks Joe :music2: :fiddle:

 

[dan filipi]

Let's see, I got up to 135 primary. With that I got almost 43 mpg.
I know if I went down from that just .05 it was lean.
Are you still running with the power valve?

 

[canuckxxxx]

dan filipi » Fri Sep 18, 2015 8:34 pm[/url]":1xacdcif]
Let's see, I got up to 135 primary. With that I got almost 43 mpg.
I know if I went down from that just .05 it was lean.
Are you still running with the power valve?

Power valve removed.

Note Dan, that Calgary is about 3000' above the sea so leaner jetting is required. Also If you are at SL then you are making more power at smaller throttle opening than I am.

 

[canuckxxxx]

I'm still wanting to get my 1200 heads ready and put them on. But one of the cams has a scored lobe as well as it's rocker.

image

• canuckxxxx
• Oct 10, 2015

image

• canuckxxxx
• Oct 10, 2015

Do any of you guys have a 1200 cam that you can sell me? Are they all the same from year to year?

Thanks
Brian

 

[slabghost]

Should all be the same I think. You can smooth the effected areas with a whet stone. My spare set is in Indiana and unavailable to me. I'll look around I may have another set here.

 

[Denver]

Looks almost like rust pits on the cam :headscratch: If they weren't over revd,(floated) & is pits from moisture, & neglect, you should be O K. :salute: