very good idea!

talking of rods i think the new gx series motors you dont really need to change the rod as soon due to some of the nip taken away IMO they run alot easier my MG66 i havent even changed the rod yet done 1a little over 16 lt through it still measures up the same as a new one no slop at all :D

I think with the crank being slightly bigger with the plating on the Gx series the rods seem to come off a little harder. Basically if you don't have to do it wait until you have some fuel through the motor.
It is best to put a clutch or a piece of tubing on the end of the crank to hold it back when taking the rod off the crank on a new motor. There is a picture of my tool I made quite a few pages back.

Rex

Do the gx-7r's have different timing? basically how much am i missing out on with my 5.5 gen?(yes i know about the coating) but performance wise any real changes? minus the carb which might be better, but again i dont know.

IMO the new GX motors do perform better than the 5.5's. Possibly to do with the carb and the crank. They do tune easier (we have the long needle version here, which I believe gives smoother performance). My customers and I have now run all three models under race conditions, and the new motors just have more performance right through the power band it seems.
I rebuilt my old Gen 5 7 Port (which had a Gen 5.5 crank fitted). Put a new GX PRS set and GX coated crank into it, but retained the older long needle Gen 5 carb. The motor is wicked. More power than the old 7 port ever had, even when it was new.
As I said before, that's only my personal opinion, so it would be interesting to hear from other users who have upgraded from the earlier models to the newer GX Series.

I'v now passed the 20 ltr mark with my MG66.

Still original main bearing and rod, spare's still in my box.
The boss (Mark) asked me to bring her in for a measure up etc...

MM asked, you sure you been running this thing, if it wasn't for the carbon around the porting he would have assumed it was new. ;)

Main bearing still fine, no slop on conrod/crank pin....crank pin wear measured only 0.003mm after 20+ littres :lol:


or was it 0.0003mm ?

I'm not sure if I'v typed that rite, I'm sure Mark will correct me. :D

Just got my engine in the mail, the guy said 3 gallons had run through it, the engine is in GREAT shape and still has some serious compression wow :) i can't believe i got it for 70 bucks lol
couldn't pass up that offer, also i have a P/S/R in the mail as well as ceramic bearings. can't wait to start her up.

throw in a new rod and put a few more gallons through it,then rebuild. I have a 7 port with 12 gallons through it and have only replaced the rod 3 times[1st rod after 2 gallons,then every5 just cuz] the bearings in these engines last a very long time. ofcourse I use after run oil and preheat before I fire mine up. also save up and get the new gx-r crank when you rebuild.imo

Yea on the rebuild i am going to get the coated crank and the gx carburetor (if this one does me right i might not even grab the new carb) also there is already a gold wrist pin in my engine... guess the previous owner put it on.

I plan to save the ceramic bearings for after I break-in the new P/S which seems like it will be in a very long time.
I honestly can't believe the compression ad that it's had 3 gallons it feels new!

I don't think the new gx carb will work on the older engines. It takes about 4 gallons before it is really seated in. If you have the coated wrist pin in it the rod has already been replaced most likely. I honestly think I would just seal it up and run it. Just make sure you have the c-clip for the wrist pin seated in the slot all the way. I have seen and done one myself,get all together c-clip not in all the way even though it looked like it, it comes out so long psr! and god knows what else. On the carb. I like the carbs that have the red go logo on the front of them. for some reason they are the easiest to tune for me. One last thing.When yor engine is running great then seams to flame out or not running right. Do not assume it's the engine thats giving you the problem. I have only had 2 engine related problems. 1 was an air leak[that's why I said seal it up] the other c-clip popped off. other then that it's been broken clutch springs small crack in fuel line things of that nature. These engines setup and run in right will last a long time.

the Gx carbs definately work on the older engines no problem at all and the gen 5.5s came with the coated wrist pin so I'd say it's still stock but I'd still put in a new rod just for peice of mind:D

thank you retro,I did not know these facts. I thought I had read back a bit that the new carbs would not work on the older cases and the plated cranks and pins were options until the gx-r series. I totally agree with what retro has stated.

If any of you guys are interested in these motor holders let me know...I make them for fun. ;)

more pics

i have put the ceramic bearings in mine flanno all is very good still and going very strong , no wear on the piston or liner