Jump to content

Modified Yokes For 1986 Honda Rtl250


jerry27
 Share

Recommended Posts

Does anyone know of a company/shop who is manufacturing/selling in-line alloy yokes for a Honda rtl250?

I want to modify the fork angle but do not wish to cut the frame.

Have seen a few companies selling yokes for the TLR250, but I not the RTL. Fairly sure the TLR yokes will not work unless someone knows better?!

Any thoughts or ideas appreciated!

Link to comment
Share on other sites

 

Hi Jerry, Changing the yolks (or called triple tree) does not change the fork angle.(with regard to steering) Changing the yokes will change your castor or lead, although from an esthetic view, the forks would look more upright. I'm sure some other subscriber to this web, will be able to explain, better than I. My RTL steers loverly (pinky with disc's) i've found that the rear spring is usually where the problems are, and a new spring correctly preloaded works wonders.

Edited by ask greeves
Link to comment
Share on other sites

 

Surely if the tripple clamps are Parallel with the headstock (which the standard ones aren't), then the fork angle would have changed, just like if the frame had been cut. A new set of tripple clamps offset to the rear would give the same effect, maybe not quite as much, but better than the chopper style originals. You could try some 4rt ones with top hat spacers for the 35mm forks, but you'd need the bearings sorted I believe. Raise the forks through the tripple clamps, fit a longer rear shock, will all make things a bit better than stock. The 85/86's have a shorter rear shock than an 88/89's.

  • Like 1
Link to comment
Share on other sites

 

JJ65, Sorry mate, it's not as easy as what you say, it's the way the stanchions rotate around the head angle. If it was as easy as you say, Ducati would have won the Moto GP world championship by now. Where's all those clever dudes when you need em ! ! !

  • Like 1
Link to comment
Share on other sites

 

Greevsy, I'm not wishing to doubt you, im no expert, that was just my understanding of how it worked. Someone did suggest offset headstock bearings to me a couple of weeks ago, rather than a cut and shut job, but I believe that's also very difficult to achieve. I'd like to get rid of the tiller effect of the handle bars aswell. I know that MA and MG both recommend the forks being pushed through the clamps to lower the front end.

Let's hope an expert Pops along with some first class advice soon :0)

Link to comment
Share on other sites

 
 
 

The tlr yokes won't fit your rtl without modifying the steerer tube Jerry, I've been there and done that with my own 1987 rtl, also due to the design of the rtl yokes converting them to parallel is a no go, like you I wanted to alter the head angle but did not want to chop my own frame up, i ended up buying a 2nd hand frame off Richard Allen and modifying that,I've had the head angle done and also the footrests moved back and lower and it really has transformed the bike, plus I've still got my own frame as a back up!, give Richard a shout,I found him very knowledgeable regards the interchanging rtl/tlr bits.

Link to comment
Share on other sites

 

JJ, it depends what you want to achieve. (Bear in mind that if you change one parameter in the steering geometry you almost inevitably changes others with it)

If you want more weight on the front wheel (eg for more grip), reducing the offset and/or angle in the yokes will achieve that, as will cutting the frame to steepen the steering head. Both of those options will also give shorter wheelbase allowing a tighter turning circle.

If you want quicker steering - sometimes called sharper steering - you will have to steepen the steering axis. ie the steering head angle, not just the forkleg angle. If you cut the frame to achieve that you will also get a shorter wheelbase (as mentioned).

But if your rear spring is sagged or preload too low, a new spring, more preload or longer shock will all steepen the steering axis for quicker steering (without changing the wheelbase to any significant degree). As a rule of thumb, for every 25mm you raise the rear rideheight you steepen the steering axis (ie rake) by 1 degree which is noticeable to most people.

Still another option is if you slide the forktubes up thro the yokes you get steeper rake (quicker steering) & shorter wheelbase (more weight/grip on front & tighter turning). As a rule of thumb, for every 25mm you drop the front end you also steepen the steering axis by 1 degree and reduce the wheelbase by 10-12mm.

Obviously if you raise the rear or lower the front you also change centre of gravity & ground clearnce a little too.

If you want to read up on steering I found Tony Foale's books the best. See http://www.tonyfoale.com/book/

I have absolutley no experience with RTLs, but going by what others have said above I would think the logical & cheapest way to proceed would be to try the following in order:

upping the rear shock preload

slide the forktubes up thro the yokes 20-25mm(if you can)

new rear spring (perhaps stronger one)

  • Like 3
Link to comment
Share on other sites

 

You can gain a little with the front tube adjustment. But all this talk of longer and stiffer rear suspension seems to be brought on from the crazy vintage crowd. The RTL had real suspension and we were hopping about back then. You set the suspension to work together. Learn to hop or float to make it turn.

Link to comment
Share on other sites

 

Lineaway's point is crucial and highly informative. If you are sufficiently fortunate to own an RTL, for goodness sake, enjoy riding it and after optimising the original factory suspension, hone your riding skills to improve your results. How many home mechanics have the engineering ability to improve on HRC Honda's years of development? Do you really need to improve an RTL when it was capable of such amazing achievements, back in the day? What level of World Class sections do you aspire to be cleaning? When I ride my stock RTL, I am acutely aware that any weakness & deficiency in performance is inherent in the rider NOT the bike!

  • Like 3
Link to comment
Share on other sites

 

The 88 and 89 RTL's have a steeper steering angle (as well as many other improvements, including the front forks, the Prolink and the rear shock length), so HRC did improve the model through its production life.

When it comes to modifications, I think it's a very personal thing. I always think it's worth trying, but so long as it can be reversed to original spec if required, so chopping the frame is quite drastic, unless you have a spare frame. However, I will be doing the footrest mod.

Edited by shedracer
  • Like 1
Link to comment
Share on other sites

 
 

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...