'84 1200 engine for a '82 GW

[canuckxxxx]

Here is a shot of the 1200 head with the 1100 cam/rocker assembly. You can see the oil port below the centre bolt

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• canuckxxxx
• Jan 10, 2017

Here is where the oil enters the rocker assembly

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• canuckxxxx
• Jan 10, 2017

This is the plug I will use. It's 6mm set screw. It's on the end of an Allen wrench.

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• canuckxxxx
• Jan 10, 2017

Here is where it will go.

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• canuckxxxx
• Jan 10, 2017

 

[ekvh]

Most people say to take the published horsepower numbers with a grain of salt as Honda never backed them up. The fact that the 1100 had barely an increase in horsepower despite adding 100cc's makes me wonder about them. Horsepower numbers begin to add up with rpm increases, and the 1200 had a lower redline. I figure the lower redline was due to the hydraulic heads. If true, there may be a lot more horsepower available with solid cams and letting them rev more. What happens to torque in the equation is another matter.

The flip side which isn't seen mathematically for most of us with these engines is the speed at which the fuel/air charge is moving. We don't have the equipment to measure that. The 1200 had big carbs with small venturis coupled with the smaller runners and valves.

My hybrid ran great with 1200 carbs going into 1000 heads. Wish I hadn't cannibalised them.

 

[joedrum]

this will be interesting build .....torque sheesh hooch has torque big time over 1200 stock bikes ...big time torque against any bike ...if i had to really try and judge the power curve on the hooch bike ...yes it will hit mid high rpm in todays standards id say 10,000rpm ..but you have to consider gearing ....if you run that high it takes you passed the best spot to start out in the next gear...i usually never go past 8000rpm before shifting gears ....its my belief or opinion the longer stroke of the 1200 motor adds torque lower in the rpm ..super usable torque ...something you dont want to pass by going to far into the rpm of the gear your in ...my experience is really just in 2 and 3rd gears ....1st gear is way to wild to play with safely and i also feel power is in the zone it could tear up something big time ...with the parts like totally non existent i always get rolling good before i add power to first gear ...like roll on power thing .... personally big runners and SCC set up has no weak spot on my bike ...the carb is quite big also .....so its my opinion the smaller intake valve will probably cut torque a bit ...witch might be a good thing LOL....when you can run around in 5th gear at 1200rpm and pull out of it with no balking from the motor thats torque in my book ....if there is anything that i might do that i thought might bring even more torque and power it would be modding the linkage even more than i have already to kick in the second barrel on the carb sooner ....im rather sure the motor would just eat it up

 

[ekvh]

My gut/butt tells me 7-8k is best shift point also, and third gear is enough to lose your license. Wish we all had unlimited money to test with Dyno and/or racetrack---- just so we'd know for sure. I also wish someone could do some flow research on the heads, wish wish wish.

 

[dan filipi]

Interesting project, Brian. I'm following.

 

[canuckxxxx]

So I went ahead and drilled from the base of centre bolt over to the rocker oil feed.

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• canuckxxxx
• Jan 11, 2017

Then I tapped it for a 6mm set screw. Here you can see the set screw in place.

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• canuckxxxx
• Jan 11, 2017

My thinking here is that if I am using the 1100 rockers I will put the set screw to block the oil to the 1200 exit point (see post 581). If I am using the 1200 rocker setup I will put the set screw to plug the 1100 passage.

 

[joedrum]

seems great ...to me ....as far as the rocker line pins go ...im thinking this is not going to much a problem once all together and tighten down ....should be able to figure witch way to maybe stabilize it .....

i can tell you that the early 1000 cams in the 1200 head will hit the pistons.....i tried it ...so i know this as fact ....deal is the 1200 piston top out higher than the 1000 and 1100 motors

i once modded a pair of 1200 heads that used mechanical fuel pump and 1000 ignition ...but scraped the project after figuring out i didnt have the Clearance needed .....

im thinking 1100 cams might not hit but it may also hit pistons too....so this will be interesting ...if it was me id knotch piston and make sure theres no problem ..

 

[canuckxxxx]

Thanks for the heads up Joe. I will definately check it.

Was reading the Story of Hooch recently and I thought you got around the valve hitting problem by timing it using the "1" mark instead of the "T".

Thanks
Brian

 

[joedrum]

nope i probably tried that but in the end it was notching pistons ....this turned out great as i learned the flow increases ...right at the get go piston stroke with a bit more room and porting like milling to piston just right ....plus now i have room than stock motors as far as valves hitting ....it wasnt that hard to do ...but i do have smart hands with a lifetime of tool use ....grinders can be wicked ....others used old head and valve with a cutter or sticky sand pandpaper on them ...you cant see a thing like that ...to me grinder was much better and i could see my work and do it just the way i wanted it ...

 

[ekvh]

Interesting, Canuckxx. I was looking at lobe heights in the manual. Intake will gain 1.2mm lift and exhaust 1.0mm. I'm not familiar at all with hydraulic valves. Are the springs going to take the lift or are you thinking the 1100 springs and rocker assemblies? I didn't think they'd reach. Chances are pretty good you won't need the notch because you're using the same heads and valves so they line up properly. The 1000/1100 valves came in at a different angle and placement.

The numbers for lift using the 1000 limits are the same for intake lift and a tenth less lift on the exhaust than the 1100. So the only real differences are in duration and potential increased dynamic compression with the earlier closing of the 1100 valves.

I've always wondered how the 1100 cams would do in mine.

Joe, if I was using a grinder for piston notching, I wouldn't want to see. I know I'd lose it and gouge the cylinder wall.

 

[slabghost]

1200 pistons stand proud of the block at tdc. No chance to gouge the cylinder walls.

 

[ekvh]

0.020-0.040" you slip, lose balance, you nick the wall where the head gasket has to seal. It's a choice.

 

[joedrum]

ok when it comes to grinder tech ..here the basics ...you would want to use a worn ginder wheel that looks smooth and is smaller than new ..they tend to get very much better in operation when the edge has been work off the wheel just a bit ....you can practice using it on something else of like material ....you never push down when make a finish cut ,,this is what causes traction and bye bye grinder ...the piston knotch is completely all finish cut ...plain and simple it can go no where without you pushing down traction for it to do so ...it is very close to the cylinder wall yes ...grinders spin around 10,000rpm and actually hover and float in your hands ...like a router does ....there are pics in the hooch thread and the jyd thread that shows the cuts i made ...sheesh to bad i didnt make vids of doing it ...actually this is where im short on how to do stuff ..im lucky to do pics LOL...

i will admit my hands are well talented ...ive done all kinds of wood inlay into wood floors and furniture ...and can make a cnc machine work look like a hack job in comparison ...there is no tool on earth better than smart hands period ...the piston notch is no major deal on a scale 1 to 10 id say 4 ....just stay in bounds your fitting nothing ...you could do this totally by hand the pistons are soft really....but i wouldnt try that it really takes stout strong smart hands to do that ...

truth is ..i think dreading the thought is the biggest monster here ...i spent about 15 to 30 minutes tops doing all 4 pistons with small breaks between each one to refocus....

 

[canuckxxxx]

I have to confess I have gotten cold feet on modding my 1200 heads for 1100 cam and rockers :nea: . Having drilled and tapped the oil passages on the right head I put plugs in both spots and put air pressure to the oil supply hole. I expected to have no air leakage but was getting air escaping from my new passage to feed the 1100 rockers. Got is sealed up with sealant on the plug threads.

Decided I wanted to go with the 1100 cam/rockers so took the plug out to the base of the centre bolt. Put the 1100 cam/rockers in place. Without dowels you have to play around getting the rocker assembly front/back surfaces to line up with the head surfaces...not ideal just relying on the tightness of bolts to keep it in place :nea: .

Then I started on the left head. Took off the 1200 rockers/cam but couldn't get the dowels out...they are really stuck. Started attacking them with pliers, then I thought, this is really stupid oh2: ; I could screw up my 1200 heads and I could screw up the 1100 rockers/cams by not using the dowels. Also, if I can get it to run nice with the 1200 heads I can have a complete 1100 engine that I could sell.

So I am going back to the original plan of using the 1200 heads in OE form.

Brian

 

[slabghost]

As always..... your bike your call.

 

[canuckxxxx]

So I am slowly getting it put together :builder: . I marked the runners on my single carb manifold so I would move them all out the same amount to fit the wider 1200 engine

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• canuckxxxx
• Jan 13, 2017

The 1200 timing belt cover don't fit so I'm using the 1100 ones. Plus the 1100 covers are skinnier where my manifold return hose goes past.

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• canuckxxxx
• Jan 13, 2017

Should be able to try starting it up soon. :beg:

 

[slabghost]

Fit looks good so far. Best luck on the first of many runs.

 

[joedrum]

looks good ...coming right along ....

 

[canuckxxxx]

So I fired it up this morning. Was actually surprised that it started as soon as I hit the start button. I credit this to the electric fuel pump which had the carb full before start attempt. And it proved the my relay wiring is correct for ignition. Throttle response is very crisp...better than I have before with is bike.

On the negative side, after idling it for several minutes, I shut it off and it would not start again. I do have a weak, old battery and it seemed to struggle on the start attempt.

Valve clatter was loud when it first started and quieted a bit but never went away. This is after about 5 minutes of running. Might go through shim measurements again.

So promising but not done yet.
Brian

 

[joedrum]

hmmmm ok sounds like things went rather well brian