Suzuki 2 Strokes

I was wondering if i might have set my timming wrong? I never used a dial guage to set the timming, its a 74 gt750, the last time i set timming with a dial guage was in like 1990? i guess im getting old but i dont remember exactly how i did it, plus i dont have the guage right now. I read the book when i did the points, i turned it by hand and got the points to just start to open when the mark on the plate lined up with the index mark on the case like the book says, then i put my timming light on it, and they were all slightly off, so i moved them all to where they lined up with the index marks on the case, it ran fine. Then i forgot that the book says the timming is to be set so many degrees before top dead, and now im wondering if i did it wrong? most times on 4 strokes i just put the timimg light and lign up marks, and this is what i did for the gt750, so is it wrong? if you put the light on it, every cycl is linned up with the index marks on the case, the timming light is adjustable, but i have it set at zero, is thgis how you guys do it? The p.o. told me he had replaced the points and set timming so i took his word for it, then after having problems with the bike i checked and the points were original!!!!! one had a hole burned in it, im waiting for condensors but i have already ran the bike with the new points and it seems ok.

Although the factory manual gives dire warnings about using the 'timing marks' on the triples for setting the timing (they are really assembly marks just to help you fit the points cam & plate the right way), in practice they're usually pretty close to what the actual timing would be if you set it with a dial gauge. Of course, your mileage may vary, no warranty is given or implied, etc etc ....

In stock trim, Suzis are not particularly fussy about ignition timing, and indeed the factory manual quotes a wide range of adjustment (plus or minus a couple of degrees from the "ideal" figure).

Strobing to the marks usually gets you well within the ballpark, and is usually accurate enough for everyday running. If you can get access to a dial gauge, it can be an interesting exercise to find out how close your timing marks are.

Remember that to work properly, the dial gauge must be vertical to the piston otherwise the measurements will be slightly different if the spark plug hole isn't vertical to the bore.

Easy to work out the difference using the old three indian equation where one squaw on a hippo hide had two papoose (pappi?) and the squaws on the buffalo hides had one each.
Or in other words, 'the squaw on the hippopotamus equals the sum of the squaws on the other two hides'.

Yes I know, coat, door, 'off'.

Thanks so much for the info, I just wanted to make sure i did it right, so when you use the strobe light, you just line the plate marks up with the index mark on the case right? I was wondering if this would be the right way to use the light, and the marks? because thats what i did, so i dont know how many degrees the pistons are from top dead center, i just went by the marks and light another words. I will get my gauge back , i lent it to a friend about a year ago..... i just dont want to hole a piston, but then i would think the timming would have to be off alot for that right?

wow for a 2 stroke this thing is getting complicated, maybe its time for electronic ignition, i never thought i would give points up because usually they are easy, and i thought this was pretty easy untill i opened the book and read the actuall directions! wow,,,,,,,i just set it like i thought you would, but then again imm usually wrong when i thought something was simple, for alll i know the motor is running backwards now because of me , i dont remember 2 stroke stuff being this complicated, but then i probly never did stuff the way your supposed to i guess?, but all the 2 stroke i had owned all ran pretty good, maybe iv been getting lucky

Yep, for each cylinder, just make sure the appropriate mark on the 3-legged rotor lines up with the 'rib' in the centre of the window when you strobe it. That should be close enough. You may find, when you check with the dial gauge, that the marks are spot on.

Once again thanks for the reply, I really appreciate the help!!!!!! I got to used to working on the cbm72 hawk....or superhawk as known in the states, its a weird one 1963 250cc twin, it has dual carbs with a 360 degree crank and one set of points, my dad brought it back from japan when he was in the navy, it sat outside uncovered untill 1990 when i started the restoration, It was the longest hardest resto i have done, since some of the parts i could not get here in the states, like the coil,and cams are different because of the crank being 360 degree instead of 180 degree. This model was not ment for shipment to the u.s. so i had to go through court to get it registered and to get a title!!!

or superhawk as known in the states, its a weird one 1963 250cc twin, it has dual carbs with a 360 degree crank and one set of points

My 69 650 Triumph was that way. Both pistons moved up and down together. It too only had one set of points. Didn't have the Bonnie though. Mine was a single carb model known as the TR6.

Nice CB72.
So called Type 2(360 degree cranks) CB72s are fairly rare. Most were Type 1 with 180 degree cranks. In the US most of those were CB77s (Superhawk) where in the UK they sold more CB72s (Hawk in US speak)) because of the 250 learner laws.

To convert a 180 cam to 360 degrees, you grind out one tooth from the center splines. I have a couple of 360 degree CB72 cams here somewhere in the collection. I think you can use a C or CA 72/77 points cam too. The Dreams used the 360 crank configuration because it made more torque at lower speeds but less at the top end.

CB92, CB160/175/200 are all 360 cranks and as Coyote pointed out, so are British twins.

Back to two strokes. Most singles and twins used to have vertical plugs, and were easy to time. Some TZ Yamahas changed to a forward leaning plugs and Suzuki canted the outer plugs presumably for ease of access. Because the outers are at an angle, Pythagoras sticks his nose in and the distance down on the outers is longer at the same number of degrees. If you ever have the head off, use a dial gauge vertically mounted above each piston and check the timing that way and then see if the timing marks are close enough to use.

Thanks for the info, I had to get a regular cb72 cam and grind a spline out of it just like you said,(tz), the bike had become a rust bucket from being outside in the rain and snow and heat, I had to either replace, re-chrome, everything not to mention paint, I know of the british bikes being 360 cranks, but the honda i thought was pretty wierd because both pistons are up and down at same time and it has dual carbs, not a single, and the other problem with the bike is the coil, a dream coil wont work because of the location and set up, it would not fit right. The bike was so rusted there was not even a seat pan left!!! the bike is a cbm72 the (m) is what set it apart from other models and yes its a type II, most people have never heard of one so im pretty surprised you know what it is!!! wow, and as far as the 2 strokes, I havnt had a 2 stroke street bike in a very long time so its different, but i always had a thing for 2-strokes , since i was a kid, i learned on a 2 stroke , the last 2 stroke street bike i rode was a yamaha r5 350 the purple one, i never like that color but it was fun as hell... thanks for all the help...

Built my first CB72 in 73. Did my first CB77 professional restoration in 73/4. Raced a CB72 with 350 kit from 78 ish to around 1990. Built three racers and a couple of street bikes and more than one 350 kit in that time. Came to the US and bought three to make one good street bike and still have sets of cams, new crank webs, primary chains etc. Bought a pile of cams from read Titan in Leytonstone many decades ago for regrind cores and sold quite a few over the years.

There's a CB77 motor on the bench gathering dust and a race converted frame in teh shed waiting for their time to be right when the planets align and they get together.

wow no wonder you know so much about them, its one of my favorite bikes to ride, I know they arent as fast as todays stuff , but iv been riding my cbm72 since 1996, with no problems untill recently, I had it bored out, new pistons, i put it back together and i have a head leak, so i took it apart again and i thought it was the gasket so i got a better gasket, and new o-rings i checked everything out and used copper coat on the head gasket and it was fine untill about a month ago i have another head leak? i have not re-torqued the head bolt yet like your supposed to , but im wondering if it might be warped and i just didnt notice or see it, i have been inside that motor a number of times but i never had a leak untill now, the superhawk is probly my favorite bike, not just because of how fun it is but because of the history i have with it, since it was my fathers, he rode it around in japan then he stripped it down and sent it back to the states in a box as a coffee table, thats why it took me so long to get the paperwork on it.....

We'll probably get excommunicated for this thread jack, but let's live on the edge. Sometimes the dowels on teh corner studs are too long or the drilling is too short and with the head torqued down, it is not pressed hard enough against the gasket.

Another possibility is that the O rings might be too thin and not sealing the oil feed up the two outer studs.

The third possibility is that the head or barrels are not 110% flat and free of raised bits of metal or gouges.

It's possible that the gasket is a problem but that's unusual. We modified stock gaskets for bigger bores and inserted CB350 fire rings and they didn't leak.

Are you sure that the acorn nuts are not bottoming out or the washers leaking?

Well it was my thread and i guess i did jack my own thread, sorry everybody, I first thought it was the acorn nuts bottoming out and it wasnt, next im thinking its like you said, i dont think the 0-rings on the 2 studs are getting squished enough to seal, or its warped im nit sure but its pissing me off, iv had the head apart 3 times now, at 1st the leak was coming from the front of the head, and now its from the back of the head, even the base gasket was wet! i have parked it for now untill i figure out what to do , so i went back to working on the gt750. The cb72 runs great, nothing wrong except the head leak, which you know superhawks were known as one of the 1st oil tight bikes, so im going to have to find time to open it up again and inspect, i will look at the dowels i think they are the problem, or it is warped. Thank you for all your help, i wish we could have talked years ago when i rebuilt the cbm72, you would have been alot of help!