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Author Topic: 86 top motor mount  (Read 99 times)

Offline brad luna

86 top motor mount
« on: February 13, 2020, 10:55:14 AM »
I was curious was the motor mount at the top of the engine used on 86 R's?
I noticed when I pulled my engine there is a place for a bolt to run thru the top of the engine but mine did not have one in the spot and there was no motor mount plates to mount to the frame is that normal? 
Do I need to have this fixed while my engine is out?

Online The norm

Re: 86 top motor mount
« Reply #1 on: February 13, 2020, 11:50:47 AM »
If you have a stock frame there should be bolt holes for a head stay.  #2 is a head stay.


« Last Edit: February 13, 2020, 12:01:09 PM by The norm »
1986 Trx250r-- Hybrid Engineering 391(Good bye super 310)
1986 Trx250r-- Hybrid Engineering  ported stock 86 cylinder
1986 Trx250r-- craigslist engine with unknown ported 89 cylinder.
1985 Atc250r-- Needs a lot of work (Super 310's new home)

Offline 2ndmoto

Re: 86 top motor mount
« Reply #2 on: February 13, 2020, 10:07:57 PM »
there is debate about running them. There are quite a few people running big bore motors that have issues breaking motor mounts and head stays. Some have stated they stopped running the head stay and have not had anymore issue with breaking mounts.

I have always ran them. At the tail end of running an OEM frame, I was running a big bore and my frame started to break every where. Id like to believe it was I was an ultra beast and stressed the frame by blitzing whoops and skying it out. In a few more years I will probably fully convenience myself that was the case, but in reality most frames have seen a lot of hours and are starting to creep.

I moved to a different frame setup shortly afterwards and have not had issues. I am not going to advise whether to run one or not. Too many variables with some pros and cons. I will say there are a lot of people who do not run them and have not had any issues.

Maybe someone can speak to the Puma gusset kit.

best regards
-Jason

Online The norm

Re: 86 top motor mount
« Reply #3 on: February 13, 2020, 10:17:32 PM »
I installed the pumashine gusset kit on mine and have not experienced any frame failures since. I have a 391 and do not use the head stay
1986 Trx250r-- Hybrid Engineering 391(Good bye super 310)
1986 Trx250r-- Hybrid Engineering  ported stock 86 cylinder
1986 Trx250r-- craigslist engine with unknown ported 89 cylinder.
1985 Atc250r-- Needs a lot of work (Super 310's new home)

Offline 2ndmoto

Re: 86 top motor mount
« Reply #4 on: February 14, 2020, 12:31:08 AM »
Norm, do you usually ride sand? I am curious if you have noticed a handling difference. A head stay would tighten up the chassis vs not having one. There is definitely a preference and is different from rider to rider. Some like a looser chassis setups.

Speaking more to that, KTM still builds their mx bikes with a chromoly chassis, while Japanese use aluminum. The chromoly chassis will flex more, which they state is an advantage, and they have a lot of supercross and mx championships over the last few years to back that up.

-Jason

Online The norm

Re: 86 top motor mount
« Reply #5 on: February 14, 2020, 08:20:07 AM »
My R is a sand queen, but I have other machines that I use for other types of terrain. I couldn't really tell a difference after the gusset kit. That may be because I also changed front shocks at the same time. I went from oem front shocks to a set of built 450R shocks. Over all the bike has a more ridged feel which I like.  I do not like a "loose" handling bike so the combo is perfect for me.
I guess I should only change one thing at a time so I can see if it makes a difference, but I don't have time for that. I usually stock pile parts until I have everything then go nuts on a weekend swapping things over. I'm too busy with life and definitely too impatient to do the right thing lol
Loren
1986 Trx250r-- Hybrid Engineering 391(Good bye super 310)
1986 Trx250r-- Hybrid Engineering  ported stock 86 cylinder
1986 Trx250r-- craigslist engine with unknown ported 89 cylinder.
1985 Atc250r-- Needs a lot of work (Super 310's new home)

Online croat1

Re: 86 top motor mount
« Reply #6 on: February 14, 2020, 08:57:13 PM »
As Jason mentioned...many a debate have been had over the headstay question.  Interesting to see what happens to a stock frame when the headstay is taken out (how much the upper frame rails spread out).  A R fame builder told me for a stock frame to use the headstay.  The same builder said it was option on an aftermarket frame.

Joe

Online evaneyeball

Re: 86 top motor mount
« Reply #7 on: February 14, 2020, 11:29:30 PM »
i have never had a head stay and not had any problems with my frame. but the handling seems fine. but im coming from a 400ex and a 250ex. and on my R i am not pushing alot of power through it and i ride pretty soft but dont know about the guy who owned it before me. and take every thing i say with a grain of salt because i do not know everything about the 250r.
LED built 269

 

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