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will not steer worth doo doo

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I have a new 125cc SSR mini pit bike, with inverted forks.  The wheels are 14 inch front, 12 inch rear,. My problem is, it will not steer in sand at all, it just sucks the front wheel under and down ya go. it also is unstable on other terrain, by constantly over steering, and correcting steering, it wants to go where it wants, which leads me into hitting TREES.   Its not the rider, I have much experience, its my front end I think   First it was the brake dragging on disk, which came BENT, I just fixed that..  then it was too loose of a crown nut,  TIRE Air pressure was tested at all different poundages, it is now set at 16 front 15 rear. What could be wrong that I am missing?   wheels too small? ( I am trying to buy 17 inch front wheel)   I also changed fork oil, and replaced with good 20 weight fork oil, at 220cc per leg.   I even turned up the preload on front spring.  Could it  be the style of front tire?  it is Chinese copy of M51.  Could it be the rear spring is too tight, (less sag) or too loose (too much sag)?  It was bottoming, so I turned it in tighter and reduced preload sag.    HELP... I am puzzled. 

Gary

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Hi, I had the same problem in sand, the problem is the style of the front tyre, I put on a Vee Rubber 60/100 14 inch on the front and a Vee rubber 80/100 12 inch on the rear and I didn't have the problem anymore. It doesn't completely take the problem away though it just improves it.

Here is a pic of the tread of each of the tyres. The bottom pic is the front tyre.

ImageUploadedByThumper Talk1402112087.300694.jpg

ImageUploadedByThumper Talk1402120517.855415.jpg

I hope this helps. Cheers Jake.

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Thanks I will replace my front tire for sure still trying to get 17 inch front

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___JAKE___.  I will do some  measuring of entire front end area to be sure you are right.   It appears at a simple glance that even a 21 inch wheel would fit, but the ruler will do the final decision.  I never thought of the wheel not fitting, thanks for the tip.   A different tire pattern was suggested, and that idea sounds good if the 17 inch tire will not clear.  So far, I have not found a 17 inch 32 spoke rim and spokes that might fit, but I am still looking, until I measure things today anyway.  I also discovered a perfectly round tire and rim is not easy to maintain, the steel in the rim is way too soft.  I am on my second TRUING of the front wheel, and this last one it was way OUT of round.

  I wonder if anyone has a location (web page) that I can match up my front hub to 17 inch rim and spokes?

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I gave up on the larger front wheel idea for stability in the dry sand and decided to go with a new front tire instead (VEE Rubber) of so many expensive changes to the front end.   I  have moved my handle bars backwards about 2 inches from my favorite riding position for a race bike, and this has lightened the front end.  It appears my bike rode like I was sitting way up on the tank in deep sand, and we all know that means CRASHING is coming.  I also put the recommended air pressure in front tire, of 18-20 pounds, which I hope will prevent RIM damage and the need for constant front wheel truing after 3 hours of riding time. I also softened the rear shock, reducing its load on the front end by increasing the SAC to way more than I would or should use on any  bike.  I just might have solved allot of the problem, due to my last test ride did not indicate I had to constantly correct the steering, but a longer ride into areas of nasty sand will tell ALL.

Fingers are crossed

Gary

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HEY  ____Jake____,   I can not seem to find the VRM 272 14 inch front tire from VEE Rubber,  the VRM 229 tire only comes in 17 inch.  I did find two front  tire sizes, one is 60-100-14, the other is 80-100-14.   would the wider "80" tire be better in sand or worse than the "60"??     So let me know where you bought yours at.  That will help me, I do SUCK at internet searches, always have. BTW the VRM 272 has same tread pattern as the VRM 229.   

I hope you got info for me.

Thanks  :banghead:

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Hello, burnthedirt,   You must think I am new to riding in the dirt?  NOPE.. been doing it since probably before you were born, ha ha..  started in 1971.  Its NOT the rider, its the bike, and I will solve the problem of constant over correcting and bad stability in sand and loose rocks, due to the front end wanting to go where it wants and not where I want it to go.  Try to be helpful in next comment please.  What would you do to stabilize a wandering front end?

 

Gary

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slip57 i would let sime air out of the front tire and soften the suspension if it still does this after you are comfortable with the bike i would look into a steering srabilizer.

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Hello, burnthedirt.

It seems the lower the front wheel air pressure is, the worse the steering is, and I got allot of dings, or bends in the rim, from hitting NOTHING, just riding.   I also found the  higher air pressure did not allow the front tire to dig into every little bump on the trail.   To expand on the problem, if I rode up to a sandy spot, of dry sand, and it was or is deeper than 3 inches, it would GRAB the front wheel and pull it to the left or right, depending on balance point at time, if I can not power out of it, it continues to grab the front wheel until it TUCKS under tossing my weight forward and me almost over the bars, to save this, my only choice was to ditch it on its side into something SOFT. ha ha, we both know how long that luck will last.. ha ha   next fall will not  be on something soft like dry sand or a bush.   I have been stiffening up the front and softening up the rear, but can only go so far with only a few inches of travel to work with.  This is my plan, tell me if you think it will NOT work, it is to add a longer stronger spring to one of the three internal springs of inverted forks and remove one stock spring,  Then set pre-load to almost nothing, since the stronger spring should pre-load it plenty. (on front).  I ran the rear with a completely loose rear spring, (NO pre-load at all) with no help).  My train of thought is, change the front tire to a sand, soft terrain tire,  Then increase all the suspension to stiff, more so up front than rear, but the rear will have pre-load it needs to gain some usable travel, (right now its only 2 inches and I should be using all six inches of it.  But if I set the rear stiff to match racing Pre-load specs, it will over drive the front end, making stable steering worse.  What are your thoughts on these changes?  Oh I also plan on adding a new rear shock that is adjustable, and allows for more travel.    I do know know what else to do.  What I have done has helped a bunch but is not total solution yet.

  I am looking into buying a complete front wheel from Apollo brand mini pit bike, which is copy of my SSR 125 but with bigger wheels, then do the rear next.  the cost thou  is almost the same as a new bike,  sheesh

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Slip57 i think that switch the tire will help and some suspension tuning will help but in the sandand softer terrain try getting your weight back towrds the rear wheel.

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More testing yet to be done:   The bad steering, might be solved somewhat.   I did make some changes.  The front end now has 9 inches of travel instead of just under 6 inches. (made a kit to lengthen the dampening rod without welding, and added a 4 inch spring, now it has four total.)  The rear has a new shock with oil reservoir and its 3/4 of inch longer, forcing me to change the top shock mount by hand making a bolt in bracket to extend the top shock mount a bit higher and more towards the rear  tire.  (more vertical)  I can only guess it now its no less than a full usable 6+ to 9 inches, probably 8 inches, but until I remove the shock spring and run the rear wheel through the travel I will never know exactly. The new shock factory springs are a bit hard to remove, or I suck at it.   I have a new IRC, soft terrain and mud front tire, but I do not like its knobby pattern and might exchange it for something better, since I can not find anyplace the VEE Rubber front tire in 14 inch. 

  Next, find info on how to install an external oil cooler, and where to fasten the connecting oil tubes.  YEAH Where?  

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