Jug deck on newest engine build

mapbike

mapbike

Well-Known Member
Finally got the new engine together today, shaved the jug deck down 0.020" and after torquing down the Jake's Diamond Head, I checked squish clearance and have 0.028mm

Not sure what the compression will be like with this set up, but it will be extremely high no doubt, I may end up needing to make a very thin extra head gasket to bring the head up just a few .001"

When I first started getting my parts together I had intended on using a Puch 70cc Hi Hi head I have all painted up and ready, but then changed my mind at the last minute and decided to use the Jake Head, The squish area on the Jake head is very different than he Puch, Fred, Pedal chopper, pancake etc.. heads, this set my squish very tight, so we'll see how it pans out.

20150328_164805_zpsv5a3spsf.jpg


20150328_202619_zpso3xqekzk.jpg
 
Looks great! Where do I send mine to get all painted up and decked down like that one map! Ha! You need to offer this service!
 
While I have not run a Jake's head, I DO know anything that improves combustion chamber turbulence is a good thing, which is exactly what "squish" does.
Nice to see I'm not the only one using common two stroke porting tricks out here....
 
Looks really good... With that low of a squish it will have some high compression for sure... How wide is the squish band on the Jake head? and what kind of chamber volume does it have? With the right squish band you can get away with more compression which in turn will make more power. You can also use an extra gasket at the base if you got some thin aluminum or copper you can cut one out of to add more squish clearance up top as well as advance the port timing by a degree or 2 and give the engine just a touch more power up top, or you can add the extra clearance at the head for a bit more bottom end torque.
 
What I have found to be a little tricky with setting deck height is that there are more than one base gasket thickness, the ones Ive been using are about twice as thick as the ones that are most common.

Probably taking.010-.012" off of deck for a 40mm stroke engine would keep it in the safe zone if the jug was one that was originally made for a 40mm stroke engine.

I took .030" off of the jug Im running on the GT5 I put on the Green bike, it was a jug made for the GT5 type engine and for the halc breed the amount that needs to be removed for ideal compression is even more since typically the piston sits .060+ down in the hole at TDC.

If someone has all three geometry engines, kept a particular thickness base gasket to send back with the jug after it has been modified, it would be easy to set deck height for better squish for aftermarket heads and just better compression for engines using a stock head.
 
YesImLDS said:
Haha I would, just broke and can't pay for much! I'd love a nice powder coating like that! How much you selling these services for map!?
Click to expand...

Mine are just painted with VHT High Heat rattle can paint, I wish I could do powder coating, that would be excellent.

My problem is that I barely have time to do my own bike work, if I had plenty of time I wouldnt mind doing some of this stuff for others, but unfortunately between me being a fulltime working man and having a hard time squeezing my bike work in between honey doo's and my job, I just dont have the extra time to do work for others but I would if I could.
 
"My problem is that I barely have time to do my own bike work, if I had plenty of time I wouldnt mind doing some of this stuff for others, but unfortunately between me being a fulltime working man and having a hard time squeezing my bike work in between honey doo's and my job, I just dont have the extra time to do work for others but I would if I could." --Mapbike.

I feel your pain, brother!

For that matter, I spend a bit too much time, really, on bikes for myself. Whether pedal or motor. It has to be that way; if a bicycle is your regular transport then there's going to be a good deal of maintenance involved. But between that and my job, there's not a lot of time left for other things.

Sometimes I'm surprised that my wife doesn't hassle me more over that issue. But I suppose she understands that the benefit she gets is that the car is almost always right at her fingertips.

Sometimes people will ask me if I can help them get a motor bike together. I say that I'd be glad to. But that realistically they'd have to wait far too long for me to get around to it.

So I write 'www.motorbicycling.com' on an index card and hand that to them. Telling them that they'll learn everything they need to know right there.

They never follow through.
 
Same here... now that all my tools are at the shop it makes it difficult to make time to work on the bike stuff but I've been known to stay late or go in an hour or so early to get stuff done. Last week I had one really slow day so I was able to port one of my new jugs but had to leave the roofs and floors alone since I need more bottom ends and need to measure everything with everything installed to set port timing and hight.

I've been painting my parts with the duplicolor brand engine block paints and they come out really nice with that glossy powder coat look, but I may end up buying some powder coat equipment so I can do the smaller parts like these cylinders, cases, etc... I got a friend who powder coats and he does an excellent job at it but also showed me some tricks as well as that he can get the stuff in any color imaginable, his oven is big enough to do a full size Harley frame and he has a second oven that reaches 1200 degrees for the ceramic exhaust coatings like on high end headers and drag pipes etc. I'll just be happy with an oven big enough to do an engine or several small parts.
 
Loos great BUT, when I look at my 66 and they are all the same I find a dead spot in the rotation that can't be corrected without pulling it apart and changing the connecting rod journal location. Yeah, if you noted it that you know the crank will rotate near a millimeter or more the connecting rod and piston stay in position without any movement relating to the stroke. OK so big deal it's slop that's all forget about trying to correct it and or placing less load on that slop by cutting back most of the piston leaving just enough to keep the exhaust port covered. Yeah well I've got little or even less knowledge of the 66 cc 2 stroke than the dozen's of pro's building these bike how they become pro's ? WHO KNOWS, they play along I'd guess without much complaint as to why the engines are so marvelous well they are and again are not if my inspect is anywhere near correct. I'm going to attempt to correct some of the noted cause of the excessive vibration at higher RPM by removing as much of the piston skirt as possible using the lower piston ring as a guide then removing it once to piston has been cut and run one piston ring as well cutting a slot in the connecting rod.For myself I need the freewheeling higher RPM at 200 plus lbs just to get up a slight incline some may not. I can see this through or buy a 48 cc custom crankshaft working is out for now I've only got a few tools and just taking the thing apart excluding reassemble is a larger task than I could ever expect to complete. Anyway blow it up on the bench sounds better than on the way to grandmas house GIVE IT SOME GAS MAN !
 
Not sure if I figure the math Jug, a cylinder head that size is too large to be able to fire the 1/10 of a teaspoon of fuel that the internal movement will draft or pull by vacuum for each stoke and my estimate of that amount being 1/10 is likely beyond generous excluding the timing delay that thing will cause to fire the tiny wisp of fuel. In short it likely will run but if you want to use it it will have to be filled with weld completely milled flush with the deck ans the combustion chamber will be a tiny opening drilled in the thing to allow spark to travel to meet compressed fuel.. yeah the same diameter of a medium soda straw man you are a genius after all it's a shake is it not ?
 
I'm still attempting to figure in a nexus 3 speed turned off a #35 sprocket welded to secondary clutch plate on my 66 cc I'm sure the second plate will bolt up with some small amount of work. Not try'n to change the subject or should I ?
 
YesImLDS said:
I just really like the paint job with the work done on the outside of the jug as well!
Click to expand...

You can do the paint yourself at home with really good results by using a good high quality engine block paint in your favorite color.... The key here is surface prep... First and foremost is to get any and all traces of oil or grease off the part to be painted, this can be easily done with a can of brake cleaner or carb and choke spray, then let it dry on it's own, the stuff evaporates really fast and it'll be ready to spray on the first coat. You'll just need to mask off the top and bottom of the jug as well as the intake and exhaust ports, I just use the blue 3M masking tape, then cut it right to the edge of the gasket surface with an x-acto knife or razor blade.

Time to spray... almost... gotta shake that can up until you hear the ball rattleing around, then shake it for about a minute after you hear it rattling... Now it's time to finally spray...

Start with a really thin coat, just enough to give the part some color and let it sit about 5 minutes, then go back with a medium coat, let it sit for a few minutes and go in with a final coat.

When painting a jug or a head... or anything else with fins, you'll need to shoot it on, then flip it over and shoot it on again for each coat, but keep the total thickness of the paint just enough to give it solid color so it can still dessipate heat really well.

For the cases, you can give a few more coats for a smoother or shinier finish.


As for cleaners and de greasers, the carb and choke spray is mainly toluene which is a key ingredient in most paints so it's compatible, and most brake cleaners have lots of toluene in them to cut thru and get rid of all traces of oil and grease etc so look on the cans before buying to make sure they contain this, the ones that work do but the "environmentally friendly" ones usually don't and don't cut thru the oils and greases nearly as well or may leave residues that can goof up a paint job.

For good engine block paints, here are a few brands that have done very well for me in the past... VHT... Really nice, Plastikote... Good stuff too, Krylon... It's ok, but the other stuff is better, Duplicolor... Really nice and contains ceramic to make it really tough.
I prefer the Duplicolor stuff when a really tough finish is needed, but with the ceramic in it, it's probably better to use a thin coat of VHT brand on the jug and head since it'll get rid of the heat better. I've painted jugs and heads with Duplicolor before with no overheating issues before tho by keeping the coats just thick enough to give solid color, then do a few extra coats on the cases and other parts for a better shine on the finish.
 
Yes it is... and you can most likely do just as well... just do the surface prep and use good paint... it's really not hard to paint an engine. it's all in the prep and masking work that'll give you those type results, that and spraying it on with several thin coats vs one or 2 thick coats... Most these paints have those fan nozzles on the spray head that'll make it even easier to get pro like results at home.

Just get a can of engine paint and try it out on a used or scrap jug, you'll see how easy it can be.

If not, I'm still planning on buying a powder coat setup real soon and may need a jug or 3 to practice on... I went to harbor freight today to buy one but ended up spending over $180 on shop supplies and decided to get it next time... lol... But if I do buy one next time I'll do one for you at no charge if you send me the jug and cover the shipping both ways. I'll need to order some gloss black tho since all they sell there is matte black, red, yellow, and white... The other colors are gloss, but the only black they have in stock os the matte.
 
You must log in or register to reply here.
Back
Top