Author Topic: can't keep engine in frame (Read 11042 times)

PORTED R · « **on:** May 26, 2014, 11:00:02 PM »

Motor is twisting upward in the frame ,busting my front motor mount loose all day
Ran good all day then the waterpump started leaking and clutch cover started leaking tranny oil
So new wp and clutch cover gasket is in order

fearlessfred · « **Reply #1 on:** May 26, 2014, 11:39:34 PM »

If the chain is to tight it can be hard on motor mounts and when I say to tight Im talking about when rear suspension is compressed enough that the centerline of countershaft,swingarm pivot and axle are all in line with each other, that is when the chain will be its tightest

PORTED R · « **Reply #2 on:** May 26, 2014, 11:47:29 PM »

How about if theres no head stay bolt
If I'm sitting at the line and I look down and rev the piss out of it I can see the motor twist
Nate did say it would be a hard running pv 370 haha

Pumashine · « **Reply #3 on:** May 26, 2014, 11:56:47 PM »

Quote from: PORTED R;34992

If I'm sitting at the line and I look down and rev the piss out of it I can see the motor twist

The motor twists without any load applied? Hope those are not my motor mounts you are breaking!

PORTED R · « **Reply #4 on:** May 27, 2014, 12:08:38 AM »

Quote from: Pumashine;34993

The motor twists without any load applied? Hope those are not my motor mounts you are breaking!

No pumashine mounts yet
It's crazy its like watching a built car motor twist in the chassis
And its doesn't help I got a out of frame pipe ,I don't want to crack it
I'm gonna slap a headstay bolt in and see wat it does

All other motor mount bolts are nylon nuts
But the front mount keeps coming loose

Anybody else with a 370 experience a little extra vibrate threw your handlebars
Counter balancer sounds good ,no weird noise ,plus I just got it from Nate McCoy a few months back

Pumashine · « **Reply #5 on:** May 27, 2014, 12:18:32 AM »

What size piston are you running? Is it a stock CB?

udontknowme · « **Reply #6 on:** May 27, 2014, 12:27:58 AM »

since the crankshaft spins paralell with the bike it couldnt twist sideways like a car when it revs up . if the engine is moving then obviously some mounts are probly broke or the case bolt holes are wallered out

PORTED R · « **Reply #7 on:** May 27, 2014, 12:53:40 AM »

The motor is twisting up towards the gastank
Not side to side ,should of mentioned that
The only motor mount coming loose is the very front one
The bottom ,and two back ones stay tight

I wasn't running a head stay bolt either

Piston is a fresh 79mm

PORTED R · « **Reply #8 on:** May 27, 2014, 12:54:27 AM »

Cb is stock

fearlessfred · « **Reply #9 on:** May 27, 2014, 01:02:47 AM »

Quote from: PORTED R;34992

How about if theres no head stay bolt
If I'm sitting at the line and I look down and rev the piss out of it I can see the motor twist
Nate did say it would be a hard running pv 370 haha

never seen that before, but I have not owned a 370 before either

broken1 · « **Reply #10 on:** May 27, 2014, 01:39:06 AM »

Do you notice flex in the frame or any of the mounts? Have a helper blip the throttle so you can check it out closely. I wouldn't think the engine should be able to move very much if any at all. If it does you may need to add some gussets.

PORTED R · « **Reply #11 on:** May 27, 2014, 01:56:04 AM »

Ok so I I went out in my garage I pulled out each motor mount bolt out one at a time

Case holes aren't wallered
Bolts them self are fine ,I Mic'd and compared to another set of motor mount bolts I had laying around ,and all the same
But even if the holes were warped or bad bolts ,the case I'D holes are still larger then the OEM case bolt OD
So there's still wiggle room for everything to move up and down but not side to side

The only mount I'm having trouble with is my front mount

I had my bro blip the the throttle for me and the only one that flexed was the front
Case holes are good ,mount holes good

I have seen some horrible engine mounts and holes before on a car and mine being 20+ years old are good shape

I'm thinking because I didn't have a head stay on there's too much flex on top
I'm gonna pull the cb out some time soon and check it

udontknowme · « **Reply #12 on:** May 27, 2014, 02:08:24 AM »

why dont you have a head mount ? seems crazy not to

PORTED R · « **Reply #13 on:** May 27, 2014, 02:14:02 AM »

Quote from: udontknowme;35017

why dont you have a head mount ? seems crazy not to

All the fast guys don't use them out here...ha
There's just a lot of people out here in the drag world that don't use them
They just run a head stay with no bolt ,supposed to let the motor rev higher
I have a headstay on it ,but no bolt

After watching the motor move like that in the chassis ,I'm skeptical about running the frame
I didn't have this problem when I had a 310 in it ,but once I slapped the 370 in its been fighting me

johnny22 · « **Reply #14 on:** May 27, 2014, 02:41:28 AM »

I've never had a headstay on my 370 and I've never had a problem with it moving. I have broken the lower mount a couple times but that's it. I double plated it and it hasn't broken anymore