Author Topic: Rear Motor Clearance Issue (Read 7660 times)

Grande huevos · « **Reply #15 on:** March 29, 2016, 12:07:38 PM »

Quote from: JesseA420;66098

u mean the weld that u just had done, is touching it? was this weld to repair damage caused from the engine vibrating against the swinger to begin with?
the motor does sit close at the back, but ill bet the problem is a slightly obrounded swingarm bolt hole. measure it with calipers it might not be too noticeable by the eye.
if you are only an index card thickness away from your swingarm as it sits, you only need a index cards thickness of slop in
the hole for it to smack it.

Yes originally I noticed the engine leaking oil so I pulled the motor and it had a crack and a noticeable rub point on the left case and the swing arm. When I had my new motor built he bored my cases and welded the crack to repair it. The weld seems thick. I have replaced the pivot bolt bearings and the rear linkage with a kit from pivot works. All the holes line up straight the bolts go in with out much effort and the chain lines up perfect with the sprockets.... I've had several people send me pics of the engine mounts and Clearence and it all seems normal. I'll try and take some pics this evening and post them up

Jerry Hall · « **Reply #16 on:** March 29, 2016, 06:18:05 PM »

The stock frames flex and bend. I have seen a lot of broken cases that show signs of touching the swingarm but they often had over 1/16" of clearance between the cases and swingarm when you inspected them. The majority of the bikes that showed signs of contact between the cases and swingarms were race bikes that really got pounded on the track, fat guys that did a lot of jumping or the bike had insufficient suspension for the abuse the bike was taking.

The 250R frame has basically an isosceles trapezoidal shape. 4 sided structures are not very resistant to collapsing when loaded from any side if they do not have triangulation from one corner diagonally to the opposite corner of the trapezoid. The head stay used the engine to add some very crude triangulation. The head stays were always breaking indicating they were trying to prevent the 4 sided structure from collapsing. Not running the head stay allows the frame to bend and flex (collapse) allowing the swingarm to move closer to the cases.

Many guys removed the head stay to prevent the head gasket from leaking and or breaking the head stay or breaking the head stay tab off of the head. This was just another indication the frame was flexing and head stay was trying to prevent this from happening.

Grande huevos · « **Reply #17 on:** April 01, 2016, 12:57:32 PM »

Well I can't seem to get my photo bucket to bring up my pictures which is really pissing me off. But I did do some measuring this week and the stator side rear mount was off a bit from the clutch side. Not much but maybe enough to make the difference... I did some welding and basically rebuilt the rear mounts and the middle botto
Mounts and reinforced them. I'm going to reassemble tonight and hope that she clears. I'm dying to get my bike back together and get this new motor broke in!!!

PNWrider · « **Reply #18 on:** April 01, 2016, 03:56:07 PM »

I have this exact same issue on my '88 frame, changed everything out and it still rubs every once in a blue moon

Grande huevos · « **Reply #19 on:** April 02, 2016, 08:08:48 PM »

Mine touches when it's just sitting there, even after I fixed all this stuff. Pretty sure my issue is the weld that was just done by my builder.. Straight behind the front sprocket there is a half moon shape on the back of the case to form around the swing arm and mine is no longer visible and the weld actually protrudes a little past the flush point.. Time to grind some weld off I guess

JesseA420 · « **Reply #20 on:** April 02, 2016, 09:37:42 PM »

i just went and looked at mine, i have about a 1/4" between swinger and cases. without a doubt having the weld built up that far will make the weld touch it, but was the original cause of the swingarm bumping the cases to begin with extreme frame flexing, or worn out swingarm bushings? i kno this pic is an atc frame but the same idea applies, how much if any slop is in these holes i circled?

Skeans1 · « **Reply #21 on:** April 02, 2016, 10:15:12 PM »

This is on my puma I'd make dang sure it's not the swingarm

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Skeans1 · « **Reply #22 on:** April 03, 2016, 10:02:25 AM »

Quote from: Grande huevos;66044

Has anybody ever had a Clearence issue with the back of the motor and the swing arm??... I've completely rebuilt the swing arm and the rear linkage, bought new front motor mounts and just had a new motor build and my cases welded and when I went to install my motor it was touching the swinger! All the holes line up and the bolts go right in. Not sure what to do but it's killing me! I have a lone star swing arm and oem 89 frame

Could you throw up a few pictures of the area that's giving you issues?

Grande huevos · « **Reply #23 on:** April 03, 2016, 10:15:16 AM »

Quote from: JesseA420;66242

i just went and looked at mine, i have about a 1/4" between swinger and cases. without a doubt having the weld built up that far will make the weld touch it, but was the original cause of the swingarm bumping the cases to begin with extreme frame flexing, or worn out swingarm bushings? i kno this pic is an atc frame but the same idea applies, how much if any slop is in these holes i circled?

I took the dremel with a grinding wheel to the weld last night and put that "groove" back in it. I didn't make it as much as stock cuz I wasn't sure how to deep to go without messing it up and I finally got it to clear! I pulled my swing arm off when I welded the motor mounts and yes the main swing arm hole is perfect. Originally it did crack from bad bearings. I don't have quiet as much room as in your picture but it Should be all good now. I will re assemble everything today and get this beast running by the beginning of the week

Grande huevos · « **Reply #24 on:** April 03, 2016, 10:56:18 AM »

Quote from: Skeans1;66250

Could you throw up a few pictures of the area that's giving you issues?[/QUOTE

Is there a way to post pictures without photo bucket? That's hiw I've always done it but now all of a sudden I can't get it to pull up my pics. I have some build pics I want to post up too

Skeans1 · « **Reply #25 on:** April 03, 2016, 10:58:59 AM »

Quote from: Grande huevos;66254

Quote from: Skeans1;66250
Could you throw up a few pictures of the area that's giving you issues?[/QUOTE

Is there a way to post pictures without photo bucket? That's hiw I've always done it but now all of a sudden I can't get it to pull up my pics. I have some build pics I want to post up too

Tinypic or tapatalk

Grande huevos · « **Reply #26 on:** April 03, 2016, 11:05:50 AM »

Quote from: Skeans1;66243

This is on my puma I'd make dang sure it's not the swingarm

Sent from my SAMSUNG-SM-G890A using Tapatalk

The issue was directly behind the front sprocket on the back side of case where the swing arm is closer to the frame. The case has a machined out crescent shape that allows the swing at
To fit.. Mine had a crack right there and when it was repaired it was very thick and you could no longer even tell that the crescent shape was ever there. That is where i did the grinding. If I get my photo bucket to start working I will
Load some pics

JesseA420 · « **Reply #27 on:** April 03, 2016, 05:33:27 PM »

you can just attach your photo directly to your posy by uploading the photo directly to the website I think

Grande huevos · « **Reply #28 on:** April 07, 2016, 04:30:26 PM »

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Grande huevos · « **Reply #29 on:** April 07, 2016, 04:32:16 PM »

It's all good now got it to clear and she is back together

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