'84 1200 engine for a '82 GW

[canuckxxxx]

I am really wondering about what is different between my 1200 with 1100 heads and the B-girl and Hooch. When I checked valve-to-piston clearance on mine it was not even close enough to make a mark on the putty I used. B-girl and Hooch they both had intake valves hitting piston. I know both B-girl and Hooch used early 1000 cams but the difference in lift compared to 1100 cams is not that great (about 1/64").

Makes me think there is something wrong with the way I have the valve timing on mine. I have gone through both the 1100 and 1200 manuals and they time the valves the same. T-1 marks (marks on each side of "T") lined up with the marks on the case. Arrows on the cam wheels lined up with the marks on the heat shields. BTW I used the 1100 cam wheels but when I compare them to the 1200 cam wheels they appear to be the same. I took the right 1100 cam wheel off, when I had the belts off, and held it on top of the 1200 cam wheel and the marks the outside edges looked to line up the same.

Any thoughts on this?
Brian

 

[joedrum]

it is not the lift that gets the early cams in trouble ....its the duration of the lift ... it last a long time over 1100 cams lift ....as a result the early cams stay out at full lift longer allowing the piston enough time to get to it ...and it hits ... i think your fine and there no concern you have done anything wrong .. the motors do time the same way ..... opcorn:

 

[ekvh]

Duration is longer, but they each ( 1000 1100 intake and exhaust) open and close 5 degrees BTDC a ATDC. The duration is when the piston is down in the bore. Pulleys are the same, but 1200 belt has to be a little longer for the stroke difference. I'm thinking this still might be a good mod for overall drivability. Need to run it longer to see if compression comes up. They usually do.

 

[joedrum]

ok eric ... hmmm might have said differently ...ok duration is over yes ...but the piston catches the valve ...before it gets home in its seat sheesh ... hmmm i guess i think in longer steps ... to me duration is still going on till valve is safely at home .... opcorn:

 

[ekvh]

My intake is set now to open at around 8 degrees BTDC and I have had no issues, just moved the power band down a little, and yet, I still think this is pulling pretty hard at 8 k.

 

[joedrum]

there is direct corlation between piston size ...stroke....and cam timing ...and there is the perfect set up for every motor size out there and configuration ... to me its obvious what cam is best with what out there in oldwing parts .....i am not one who beleaves the garbage of varible cam timing is something important...just BS in my book retard and advance spark timing been doing this since the first motors were being born a century ago .....

i will never forget cm85 telling me i was just super lucky to get hooch to perform as i did ..that someone with no educated engineering background cant make a hooch ... i never laugh so hard in my life ... the reason i came up with hooch is i know exactly what im doing and how to get there sheesh ...to me it seems ..its the educated that are having all the problems with things ...not people with the undefeatable attitude ... this is what my degree says im good at ....

in my view brian this will be a great bike and may change some .. or maybe not ..through a proccess of figuring what you have come into focas ... being blind to some things is not a good asset in the feild of successful outcome ... great job so far brian ...the stable of 1200 modded bikes with single carbs is growing .... :BigGrin:

 

[canuckxxxx]

I know the intent is for me to ride the 1200 and hopefully the rings will make a comeback but I cannot leave well enough alone.

I knew I wouldn't be satisfied unless I knew that the valve timing was as per factory specs. because I know from my experience with my old Suzuki GS750 that valve timing can affect compression readings big time. So I downloaded a degree wheel image and mounted it on some 1/8" plywood and bolted it to the front of the crankshaft. Mounted a pointer onto one of the bolts that holds the thermostat housing. Made a steel plate that mounts onto the head via the 2 middle bolts that hold the rocker assembly on. The magnetic mount for my dial indicator sticks to that steel plate and the dial indicator plunger works on the top of valve spring keeper.

To prove that the TDC makes on the flywheel are correct I made a mechanical stop out of an old sparkplug, knocked out the insides and tapped it for a 5/16" bolt. TDC marks at T-1 proved to be right on.

For a GL1100 the intake is supposed to open at 5º BTDC and closes at 43º ABDC. These angles are at 1mm (.039") valve lift. So with everything set up (my apologies for not taking any pictures) I turned the engine over via the crankshaft bolt watching for the intake valve to start to open. When it started to open I continued advance the crank until the valve lift was .039" and check the angle on the degree wheel. Continued to advance the crank until the intake valve started to close. Continued to advance the crank until the valve opening was .039" and checked the closing angle.

Did this for both sides, cylinders #1 and #2, and got the same results. On my engine the intake opened at 3º ATDC and closed at 50º ABDC. So valve movements were all happening at about 7º later than they should be.

What to do...I remembered that each tooth on the cam wheels is good for 9º which made sense to me because there are 40 teeth so 360º / 40 = 9º. So I reinstalled the cam belts so the cam wheels were advance by 1 tooth and rechecked the valve timing. What I didn't think of is that 9º on the cam wheels is equal to 18º on the crank because it moves at 2:1 compared to the cams. So my timing was now; opening 15º BTDC, closing 32º ABDC. So I was going to give up and put it back to how it was but then I thought, why not give it a try. As long as the valves and pistons are not fighting, the worse that could happen is that it would run like crap. Through none of my crank turning was there any indication that the intake valve was hitting the piston. For another check I moved the crank to TDC and pushed on the intake valve rocker with the wooden handle of my hammer and got at least 1/16" movement so I figured there would be no harm in running it like this.

Long story I know so here are the results: bike runs much stronger now, way more low end torque which works well with the taller 5th gear on the 1200. Much nicer to ride now. Will pull strongly from 3000 in top gear. I normally run in the 3000 to 5000 RPM range and this is about ideal.

When I got home I did compression checks:
#1 155psi
#2 160psi
#3 155psi
#4 158psi

The down side is that it seems to be really drinking the gas. I will have to do a mileage check but the 3/4 tank of gas that I had was down to 1/4 in about a 45 minute ride.

Again, I am sorry for not taking any pictures but here is a pic of the stuff I used to do the valve timing checks

stuff i used to check valve timing

• canuckxxxx
• Jul 20, 2015

Brian

 

[canuckxxxx]

So the bike is running much stronger now but the valve timing is not really right. I would like to get it closer to factory specs...say...(I like low end torque)...opening 8º BTDC, closing 40º ABDC. The only way I can think of to adjust the timing would be with offset keys on the cam wheels. I am going to take a look at that.

Brian

 

[slabghost]

So you've advanced the cam timing but you are still running stock 1100 ignition timing right? Stock 1200 ignition timing at full advance with vacuum advance is 45 degrees btdc. So advancing the timing of the ignition may do wonders for performance and mileage.
I've given a lot of thought to offset key to advance timing. I suggest one offset key at the crank. That will give you the most control and advance both cams equally.

 

[canuckxxxx]

I think in the end I will try and get the valve timing closer to OE. But it would be interesting to try advance ignition too. Because it's an '84 the ignition is 1100 style with the vacuum advance. So maybe it could be advance via the screw on the vacuum canister.

I agree an offset key on the crank would make more sense but how hard is it to get the crank wheels off...do you need to use a puller? The cam wheels just slide off easy.

When I think about the valve timing I have now the exhaust valves are closing before TDC on the exhaust stroke so that is probably not ideal.LOL

Brian

 

[slabghost]

I have to defer to others on here who have had the crank pullies off. As to how difficult they are to get off. But the key there has a lot more meat to work with for offsetting. I've been considering 4 degrees over stock.

 

[canuckxxxx]

I bet you would feel the increase in torque with 4 degrees advance. Ekvh, plays around with cam timing a lot, I'm hoping he comments on this.

Brian

 

[canuckxxxx]

But Slabghost, I would suggest, if you are going to experiment with valve timing, that you check everything as accurately as you can with a degree wheel and dial indicator etc. I wouldn't assume that if timing is set up according to the marks on the cam wheels, that it at OE timing.

Brian

 

[dan filipi]

Interesting thread.

The crank pullies slide right off after the bolt is removed.

 

[slabghost]

canuckxxxx » Mon Jul 20, 2015 6:15 pm[/url]":140yrdy9]
But Slabghost, I would suggest, if you are going to experiment with valve timing, that you check everything as accurately as you can with a degree wheel and dial indicator etc. I wouldn't assume that if timing is set up according to the marks on the cam wheels, that it at OE timing.

Brian

I'd be using a degree wheel and the tdc on the crank. I have good calipers and measuring the offset shouldn't be difficult.
I think 4 degree advance at the cam is only two degrees at crank so the key needn't be offset much.

 

[Denver]

On 85 & after, wheel is on front & similar to 1500's ,those have what is called a trigger wheel by some. Under this name you could buy four or six degree advanced wheels, told that you MUST run high test fuel. Results, upped a few more horse power to almost 100, & almost 100 foot lbs of torque. Asked were they going to make one for 1200's, & said if like ones for 15's you could do your self, same way should work, :good: but not be enough people for him to bother. :crying: Seemed like a nice enough guy, think he told me the truth. :yes: Said you could move the cut out for key in crank so triggers on stock wheel were advanced 4 or 6 degrees, welding old one shut, to cut new one, if you had to. But would be nice if you had enough room for both, but you'll need at least one dooner wheel to experiment with the first time. :salute:

 

[joedrum]

hmmmmm seems just cutting new keyway in 1/2 way around cam pully off set like you want is best deal to have to me ...well as the numbers thing goes .. there no way a 1200 is going to give same reading as 1100 ... the distances are two different lengths .. so im not so sure how 1100 numbers apply to you .. im sure they do some ...there no doutb in my mind that my bike is way different than 1000 motor with same parts... for the better :BigGrin: in my case opcorn:

 

[canuckxxxx]

joedrum » Mon Jul 20, 2015 7:19 pm[/url]":32nt1hu0]
hmmmmm seems just cutting new keyway in 1/2 way around cam pully off set like you want is best deal to have to me ...well as the numbers thing goes .. there no way a 1200 is going to give same reading as 1100 ... the distances are two different lengths .. so im not so sure how 1100 numbers apply to you .. im sure they do some ...there no doutb in my mind that my bike is way different than 1000 motor with same parts... for the better :BigGrin: in my case opcorn:

I was referring to the 1100 numbers because I am using 1100 heads and cams and the setup, with the lining up of cam wheels marks, is the same.

 

[slabghost]

Keys at the cam are very thin. I'll go with the key on the crank pullies when I try it. Only one key to switch I can make several to try and just try one at a time.

 

[joedrum]

canuckxxxx » Mon Jul 20, 2015 10:33 pm[/url]":1f0a3my8]

joedrum » Mon Jul 20, 2015 7:19 pm[/url]":1f0a3my8]
hmmmmm seems just cutting new keyway in 1/2 way around cam pully off set like you want is best deal to have to me ...well as the numbers thing goes .. there no way a 1200 is going to give same reading as 1100 ... the distances are two different lengths .. so im not so sure how 1100 numbers apply to you .. im sure they do some ...there no doutb in my mind that my bike is way different than 1000 motor with same parts... for the better :BigGrin: in my case opcorn:

I was referring to the 1100 numbers because I am using 1100 heads and cams and the setup, with the lining up of cam wheels marks, is the same.

belt is one tooth longer opcorn:

its hard to say witch side the fence everything is on..one side or the other ... or both ways ... the belt tooth :headscratch: