Fuel for OPS .21 3.5cc

[Jim Zelazny jr]

Filler was one thing I was thinking about and will give that a go.As for bearings...where do I find these for an older engine like this? Thanks for tips...will start work tomorrow.

 

[FloridaScaleBoater]

Filler was one thing I was thinking about and will give that a go.As for bearings...where do I find these for an older engine like this? Thanks for tips...will start work tomorrow.

Give these folks a call, https://www.bocabearings.com/

 

[Jim Zelazny jr]

I see clearly this is a Perry carb for the records. Also...you can see the grooves or compression dents on the port.I will clean this well with fine grit and use the JB weld as mentioned.Meanwhile,going to pull the engine and look into bearing replacement soon as I figure out where and what to buy.

 

[Jim Zelazny jr]

Just saw your link for bearings...thank you !!

 

[Jim Zelazny jr]

Bearings ordered and on the way soon. I have some learning to do and get this engine out of the boat.
Jim

 

[Jim Zelazny jr]

I became a bit frustrated today but stepped back and thought a bit after removing the engine and started to remove crank cover when one of the heads of the bolt broke off.No big deal as I was able to get the bolt out easily and the other 3.But will need t replace them with new.Then...see there is a gasket for the cover and left it alone for now until I am sure I can find a new one for this.I went ahead and removed the cylinder head which was simple enough and carefully slipped the piston sleeve out while observing the orientation.Decided to stop what I was doing and look online how to replace these bearings when they arrive and was a bit bummed out.Either I need a special removal tool that cost 100 bucks or some are talking about placing the engine in the oven for 30 minutes @ 300 F ? This worries me a bit as I do not see buying this tool I will probably use once in my lifetime and if this oven idea fails...then what?
Am I over thinking all this and someone has a trick removing these bearings ? Meanwhile...slid the driveshaft out and greased it up nicely.Will work on carb issue soon but the bearing part is my main focus right now.

 

[Jim Zelazny jr]

Hoping this bearing job is as easy as this guy demonstrates -

 

[Jim Zelazny jr]

Ok...I guess I am now in it,to win it !!
I am not an expert,but the bearings look like crap to me ! I am glad I tooK the advice here to replace these.They roll smoothly,but lets face it...they look atrocious.
Now the million dollar questions...
I probably should remember the orientation the piston originally was removed even though it is the same all around physically? And should I try this heating the block method to remove the old bearings/replace new? Going to clean this all up nice and careful,organize and prepare to install once new bearing arrive.Also still need to work on the carb repair.Still looking for the crank cover gasket and new bolts. So far,sent an email to this company for these items - https://gotnitroonline.com/
Any others will be appreciated.I would like to get this back together asap.Summer`s are short in NY

 

[Terry Keeley]

The video isn't bad, you don't need a hot plate though, just heat the whole case in the oven at 300* or use a torch and heat the bearing areas. That rear bearing might take a bit of heat and several raps on the bench to get it out, it's a mess. Good thing you decided to change it!

When you get them out you should clean up the case (especially the bearing pockets) with a toothbrush and some Ajax or other mild cleaner. I like to put the rear bearing in first with the crank (balls out) then find a small object (block of wood etc.) to hold the crank in as you rest the rear of the case on the bench. Then slide the front bearing in on the crank and into the case, this way it helps to guide the front bearing in. To make sure the bearings are seated in their pockets I find a socket that matches the OD of the bearing but's just a little under. Remove the crank while it's still warm and using the socket gently tap on it to seat the bearings. You'll feel a solid "thud" letting you know they're in. I've since turned up some aluminum pieces that register on the I/D but the sockets workfine, just be sure you don't slip off the outer race.

Then assemble the flywheel and put your cable collet on with a little locktite while it's still warm. To tighten the collet don't use the holes in the flywheel, put a small dowel or other piece of wood down the case from the top and jam the crank pin against it as you tighten the collet, make it tight!

The crank should spin completely free, let it cool down on it's own, if you cool it fast with alcohol or whatever it'll warp and bind. You should feel a little end play in the crank, that's the internal clearance in the front bearing. It should continue to spin freely when completely cool.

Those rear case screws are metric, probably 3 mm. The hobby shop should have them in a cap head style.

Be sure to note the orientation of the piston to the sleeve, it wears in that way. Also the lower rod bushing may have a champher on only one side, that must go against the crank to clear the radius on the crank pin.

Gotnitro is done as far as I know (owner passed away). Someone here probably has a gasket they can send you, I'd ask in the for sale section.

Let us know how it goes...

 

[Jim Zelazny jr]

I will post all progress here as it is good for others when they need help.
The original case cover screws were flat head types and one of the heads broke in half at the slot.
Luckily enough to grab with vise grips to remove.I will try the oven idea as it looks straight forward to do.Going to get this all cleaned up and ready for assembly while waiting for bearings to arrive.Later today will try the JB weld on the carb issue discussed earlier.The guy at Perry carbs said he will replace the body for me @ 20 bucks...but rather try the fix instead.Every penny counts as learned with my J3 piper cub build years ago Thank you again for help...will be asking more questions here that is for sure.I still would like to know if piston should be placed back into sleeve the same way it came out ? I see nothing different all the way around it that looks as if one way is different from the other.I do know the sleeve has large exhaust port that goes obviously on the exhaust side when placed back in.I do not think the head matters,it too looks the same except orientation of the water nozzles.No gasket was seen between the head and cylinder...nothing is there just like my K&B engine...so assuming no need for gasket except for special applications I read on other posts regarding fuel people use?

 

[Terry Keeley]

I will post all progress here as it is good for others when they need help.
The original case cover screws were flat head types and one of the heads broke in half at the slot.
Luckily enough to grab with vise grips to remove.I will try the oven idea as it looks straight forward to do.Going to get this all cleaned up and ready for assembly while waiting for bearings to arrive.Later today will try the JB weld on the carb issue discussed earlier.The guy at Perry carbs said he will replace the body for me @ 20 bucks...but rather try the fix instead.Every penny counts as learned with my J3 piper cub build years ago Thank you again for help...will be asking more questions here that is for sure.I still would like to know if piston should be placed back into sleeve the same way it came out ? I see nothing different all the way around it that looks as if one way is different from the other.I do know the sleeve has large exhaust port that goes obviously on the exhaust side when placed back in.I do not think the head matters,it too looks the same except orientation of the water nozzles.No gasket was seen between the head and cylinder...nothing is there just like my K&B engine...so assuming no need for gasket except for special applications I read on other posts regarding fuel people use?

The piston needs to go back in the sleeve the same way as noted above. If you didn't mark it look for darker areas, that will be the exhaust side. Also the rod may be champhered on one side only as above.

If you post the diameter of the carb's shoulder someone might send you a free K&B red carb or similar that has an aluminum body, would stay in much better.

You should have at least one head gasket, again I'd ask in the for sale section, maybe someone will send you a nice "care package".

 

[Jim Zelazny jr]

I sort of figured the piston should go back the way it came out.
Learned this when building Chevy engines...same procedures was my thought but good to know for sure.
I do remember how it goes back in...but now will mark it in case it gets moved.
As for carb...will see if I can patch it up and if not...will post that when the time comes...last step anyhow for now.Will check sale section now and see if anyone has supplies needed...tnx again...will get this in the water yet !!

 

[Terry Keeley]

Also the closed end of the wrist pin should face the exhaust so the hot returning gasses from the pipe don't heat it up.

 

[Jim Zelazny jr]

Still looking for gasket and bolts. Wonder if I can make gaskets and find bolts at local hardware store ? I checked the head and see no sign of previous gasket being there.As for the water jacket I think some RTV will do there as it is for water,no pressure really.Not getting replies from any of the hobby or engine websites.I do not like having stuff apart for a long time...bad things can happen over time.
Will see if someone replies but think weekend will not hear from anyone until next week.

 

[FloridaScaleBoater]

Still looking for gasket and bolts. Wonder if I can make gaskets and find bolts at local hardware store ? I checked the head and see no sign of previous gasket being there.As for the water jacket I think some RTV will do there as it is for water,no pressure really.Not getting replies from any of the hobby or engine websites.I do not like having stuff apart for a long time...bad things can happen over time.
Will see if someone replies but think weekend will not hear from anyone until next week.

PM Joe Wiebelhaus on here,
Joe used to have OPS 3.5 (21) stuff,

 

[Jim Zelazny jr]

Will look into that...Dennis is looking if he has stuff now.
https://gotnitroonline.com/

 

[Jim Zelazny jr]

The connecting rod has a small hole...maybe see it in this image?
Photo is as if looking at it IN the engine from back.And yes...I see the closed end of wrist pin opposite of exhaust.Good stuff to know.I refer to the rear of engine where the crank case cover is?And I hope the wear on that crank is normal .

 

[Terry Keeley]

The wear marks on the crank are probably cause the bearings are fooked, you can smooth them out with some 400 grit paper but try not to touch the forward part of the large diameter, that's where it seals in the case.

You'll need a new rod as well, that one is toast, the bushing should be in the aluminum part.

Yup, front is the collet end.

 

[Jim Zelazny jr]

So that bushing is supposed to be pressed in there? That answers my own thought as to how that was supposed to line up with the holes and stay lined up Glad I took this apart now.Only bad part is finding all this stuff.

 

[Jim Zelazny jr]

Am I in trouble with this engine with the connecting rod being shot?
I found this,but not sure if it is the one I need.
https://www.ebay.com/p/Vintage-Ops-...ally-Version/839050735?iid=370675887441&rt=nc