Universal con rods

Forum rules
Please can you post items for sale or wanted in the correct For Sale section. Items / bikes for sale here will be removed without warning. Reasons for this are in the FAQ. Thanks
Indiana Jones
Site Supporter
Site Supporter
Posts: 141
Joined: Mon Jul 20, 2009 8:48 am
Bike owned: XT600Z,'10 TE250 ,XS650 chop
Location: Faugheen
Contact:
Universal con rods

Post by Indiana Jones »

While stripping my expired race engine,I discovered that a con rod marked for rear use was used in the front cyl and its corresponding rear cylinder was using a front con rod.
This had obviously been done to match the con rods with the crank.
It had been working the finest and had nothing to do with my engine failure.
Anyone one got an opinion on this?
The front cyl with the rear con rod was the one that ate a valve.
I have a matching con rod(rear) to replace it,as it didn't seem to make a difference, I reckon it's a
good substitution.
User avatar
mo haggs
Site Supporter
Site Supporter
Posts: 618
Joined: Thu Jun 19, 2008 1:02 pm
Bike owned: bikeless
Location: belfast, n.ire
Re: Universal con rods

Post by mo haggs »

Indiana Jones wrote:The front cyl with the rear con rod was the one that ate a valve.
.
i think that was more to do with the fact that you force fed it,
not so much the rear rod in the front cyl. :lol:


i don't have a clue as to what difference it would make but i am interested to see what answers you get.

hope you get it sorted soon.
vic-vtrvfr wrote:they're like rocking horse poo with sprinkles of unicorn horn on top.
hunter
Site Supporter
Site Supporter
Posts: 1292
Joined: Thu Nov 20, 2008 1:09 pm
Re: Universal con rods

Post by hunter »

I have read somewere i think on this forum that it is imperative they are installed in they'r correct places,
I believe its to do with an oil pickup hole in the rod.
Indiana Jones
Site Supporter
Site Supporter
Posts: 141
Joined: Mon Jul 20, 2009 8:48 am
Bike owned: XT600Z,'10 TE250 ,XS650 chop
Location: Faugheen
Contact:
Re: Universal con rods

Post by Indiana Jones »

The oil pick ups were in the correct position,the con rods were turned 180 deg on the crank.
Was wondering why it was difficult to read the numbers on the rods when I had the sump off.
They were facing the wrong way.
NZgatch
Settled in member
Posts: 26
Joined: Sun Jan 09, 2011 1:47 am
Re: Universal con rods

Post by NZgatch »

I wouldn't have thought it would make an iota of difference, provided the oil holes lined up. It's not like the dimensions will change from front to back.
Indiana Jones
Site Supporter
Site Supporter
Posts: 141
Joined: Mon Jul 20, 2009 8:48 am
Bike owned: XT600Z,'10 TE250 ,XS650 chop
Location: Faugheen
Contact:
Re: Universal con rods

Post by Indiana Jones »

Exactly, that's the way they'll be going back coz that's all I have.
Indiana Jones
Site Supporter
Site Supporter
Posts: 141
Joined: Mon Jul 20, 2009 8:48 am
Bike owned: XT600Z,'10 TE250 ,XS650 chop
Location: Faugheen
Contact:
Re: Universal con rods

Post by Indiana Jones »

Interestinger and more interestinger.
The big end bearings all have 2 extra oil holes in them,so each bearing has 4 oil holes.
I wonder are these modified or are they bearings from another compatible model.
Edit: Single hole bearings are OE, all new bearings have two holes.
I love learning new stuff.
rvfhonda
Settled in member
Posts: 12
Joined: Fri Aug 01, 2008 6:04 pm
Re: Universal con rods

Post by rvfhonda »

Hi,
The rear conrods are 2g's heavier than the front. So at speed the gyroscopic or rotating mass will be magnified. Without seeing the engine myself couldn't say that caused the failure but just wanted to say that there is a difference between the front and rear rods but only by weight.
Mike @ BMC Racing.
hunter
Site Supporter
Site Supporter
Posts: 1292
Joined: Thu Nov 20, 2008 1:09 pm
Re: Universal con rods

Post by hunter »

So you will get crankshaft imbalance then,There is always a reason why these component's are marked.
andreasmkr
Settled in member
Posts: 102
Joined: Sun Nov 22, 2009 8:00 pm
Bike owned: Honda NC35 RLR Stage III 94'
Location: Trondheim, NORWAY
Re: Universal con rods

Post by andreasmkr »

This is what happenes when you missplace the con-rods with the crank!

viewtopic.php?f=24&t=29560

Post Reply