Alright, so I guess I am going to tear my GO .21 5 PORT MODDED engine down and rebuild. It is 2 Gallons of Trinity 30% old. I think the front bearing went. The engine was acting like it had a nasty air leak and the lower crank case was getting wayyy too wet for me to be comfortable. Looking for some advice on how to rebuild this thing. I figure I might as well either replace the piston and sleeve or at least get it repinched.
1. Where do I get a main bearing for this thing?
2. How do I change out the main bearing? I have heard about an oven?
3. Are there other bearings I need to chang out while its torn down?
4. I am clueless as to what to do with the piston and sleeve.
5. What about other internals? Am I replacing anything else???
THANKS!

Since you have it apart you might as well change the rod and piston pin and clips. I charge $35.00 to rebuild and replace bearings, rod, etc. This would include pinching the sleeve if it needs it, also includes return shipping in the Usa. Here's a breakdown of the parts cost, I usually have all this in stock. A new piston and sleeve is a pain, you have to go through the whole break in process. I have pinched motors 3-4 times.

Rear Tko ceramic $22.99
Front Tko ceramic $15.00
Go rod $18.69
piston pin $3.39
clips $1.69

I use a bore guage to check the rod, if it is worn less than .001 I would just leave it.

Rex

Motor ran great for 2 hours of practice today. However, I noticed a fin broke sometime during the last tank of the night. I went ahead and ordered one of the Donut Racing heads, but does anyone know if the Gen 6 heads have any improvements in this area?

Does anyone know if you can turn a 7 port into a 5 port. Looking at the parts listing it is the same for the 5 and 7 block. If so do I need to shim it any different.

The only difference is the sleeve..If you fit a 5 port sleeve into the 7 port crankcase ..voila!.. same rod piston crankcase/crank etc..obviously if you change the sleeve you need to fit a new piston etc at the same time..

If nobody wants to buy my MM stage 5 7 port p/r/s I'm goig to keep it and just fit it to my 3 port R when it wears out..mind you once my MG66 arrives I don't think my 3 port will be getting much runtime..

Dunut Racing Heads are aewsome. I have the low profile 1 and like it alot I think its 1-2 fins lower. Fins I have seen break on stockers is when the body hole for the head doesnt have enough clearance and hits a fin constantly and 1 will break. I have never seen a top fin break. I think the new line has some cooling holes which is cool and makes it alittle lighter. MattyB I see no need for a pinch at 2 gallons. My PTM 5 port is coming up on 4 gallons and is still tight, I say I will get at least 4 more out of it. I at 2 gallons did TKO's rod pin and clips. My Powerhouse 3 port I will not be changing the rod at 2 gallons probably 4. I heated it every time I fired it and it only got stuck once and its broke in now. I will check the rod but I know it wont need 1 as early as the 5 or 7 ports. I want to put 1 of them 100% ceramic bearings in the rear of my 3 port when I can find 1. If it aint $50 LOL.

anyone got donuts contact info and/or a photo of these heads?

I found the site:
http://donutracing.com

PM sent

Dean-Donut has a thread on here. If you cant contact him PM meI have his number.

Well, to grizz/matt- I tried changing the bearings on my 7 port today. The engine is not broken in yet but developed an air leak around the front bearing. As you know I asked for help. I got help. I watched the utube video of the guy heating up the block and hitting it firmly on the piece of wood-that did not work for me. In the oven for 45 minutes at 300 also did not work for me. It helped when I used the ofna puller/installer. actually when I do my next engine I will take a heat gun and warm case up that way. what a pain in the ass. I also managed to kiss my ebmodded 5 port good bye. I am totally to blame for this one. c clip pooped out ruined every thing except for the crank. which by looking at it must have already pretty much gone when I replaced the wrist pin con rod. It fit good when i installed because it was ovaled. Had I mic'ed it I would have known. Newbie mistake. One other lesson I have learned never buy used engines or electronics. So as soon as I let the sealant dry on this engine I am going to check for leaks and hopefully I will have to stock 7 ports that I can use until the new go engine line comes out. All in all I am glad I tried this only because I learned something. :lol::weird::cry: all at the same time.

malik you should have stayed the other day we got it all in with good results. Although I broke a fin on the motor. Im finding that this seems common in these motors.

Wow :eek: you had a couple of bad days there mate !!! Did you get the bearings out in the end with the OFNA tool and heat gun ? They can be tight sometimes, a bit like the sleeve senario. Some come out, others don't.
That is the beauty of the GRP puller I keep going on about (the one we can't afford :smile:). It has a set of expanding fingers that screw out and grip the inner race of the bearing. You can then pull the bearing out cold if you need to :weird: but I wouldn't. I have just ordered the OFNA puller last night after giving it some thought. I just can't justify around 300 of our dollars on something I might only use a few times a year.
That's sad about the EB Mods too. BUMMER. Never mind, a stock 7 Port with .3 or .4 mm of head shims fitted (25%) and a 2072 will be more than competitive :nod:

Ok my head hurts now from reading the last 50 pages or so. I believe I read on here(can't remember when) that someone is using fuel tubing as an o ring replacement? I have a stock 7port believe gen 4 or 5. I run on 20% with only 1 copper shim(plus button) i believe .4mm total as i recall. Are the carb settings given in these last few posts ok to start with on 20%? It seems that most of the posts refer to 30% I'm using 20% as I was told that it is easier on the engine. Is this correct, my boys and I don't drive well enough yet to need the extra power of 30%. Just looking for reliability and ease in tuning. We run OD plugs 97T but just ordered 77T's also and engine usually only gets to 190 or so.

Hi Babygrand48, welcome onboard the thread. Wow, you must be totally warped after reading 50 pages of our ramblings :lol:

20% is fine, and is a little easier on the motor overall. Tuning won't differ too much. You normally will run a little richer with less nitro content as opposed to settings for say 25%, but it's only a small change.
With 20% the warmer 77T's will probably go better. Should give a better idle and smoother running with the 20% fuel. You could also try an OS P5 too (med/hot).
Shimming sounds OK at .4mm total for the 20% with med/hot plug.
The fuel tubing O rings work great (that was me). If you can find the post about 5 - 10 pages back it tells you all the details. If not, PM me. :cool: