KX80 lowering

[FROSTY:Me]

Thanks guys for all the advice re bikes for my youngun.
Ive basicly set my sights on a KX80 and doing the two head gasket trick to tone it down a bit.
Only thing is hes still a bit short for it and stands tip toe on it.
Looking at the front end it looks like I can loose 20mm in the front no worries sliding the forks through the clamps.
I was told that by softening up the back spring it would lower it a bit but I figure that way he'll be bottoming the shock out everywhere.
Would a set of longer than stock dogbones be an idea??
Please could you advise

[trumpy]

You can buy lengthened links to lower the bike. I did this for my son when he first got his KX85 (instead of buying a small wheel version first and then having to change when he got older). His ones actually came with his bike as the previous owner had done the same thing but I know he had bought them from a bike shop.
Pretty easy to make if you know what the distance should be between the holes (sorry Frosty my brain is a bit old and decrepid and doesn't retrieve this sort of info any more) but a Kwaka dealer should be able to tell you.

[Reckless]

yes my boys KX85 had longer dog bones in it. They where made out of a bit of 1/8th strap probably about 20mm longer?? easy to put in and out as well.

Secondly might be easier to put extra base gaskets in! Changes the port timing a bit but if your lowering the compression by that much its neither here nore there.

[Danger]

Be aware that these so called lowering links have no effect on the over all travel of the shock. So for a full size bike (for ease of discussion) that has a full 300mm of travel all you are doing is moving the start and end swing arm position. You still have a full 300mm of travel. You don't have to look at the underside of the rear guards of too many bikes to realise that safety margins are already tight. If using a lowering link I hope you don't sit down too much because you could end up removing a Michelin from your rear passage. There have been cases of the rear wheel slamming into the rear guard resulting in spectacular ejections. Same deal with sliding the forks too far in the triple clamps. Most bike manuals recommend 10mm only. If exceeding this you need to remove the springs and run the forks through the full travel on the bike to check that the front wheel does not bottom on the underside of the guard, the pipe or the frame. You also need to consider the effects of different tires and perhaps mud build up if safety is a priority.
There are certainly shops that will sell you and fit these. Your safety is not their priority and I know of a shop that has fitted these to a bike recently, but the owner is going to have the job done properly in the next few weeks and the link is going in the garbage as I refuse to have anything to do with a bike that has one of these fitted.

Most bikes can be lowered internally and need to be looked at in a case by case basis, using spacers and in some cases shorter springs. If your concerned about only 10mm its probably best to wait a month or two for the little one to grow that much and if hes on tip toes its not far off. Or perhaps look at lowering the sub frame seat etc.

Reckless if you value your boys safety please remove the spring from the rear shock, refit the shock and check for travel issues. Factor in the last inch or two of compression on the bottom out bumper. This is an important part of the rear shock and controls the last few inches on all shocks and is meant to compress to almost nothing.

[Reckless]

Thanks for the warning Danger but they where on the KX85 we had. The extended dogbones where in when he was learning, so no hard riding/jumping to push the suspension to anywhere near its max. And I looked at all the issues you suggested B4 installing the dogbones, even cut 2" out of the seat as a compromise as well. Wasn't long till he grew into the Factory ones and I'd glued the foam back in and recovered the seat. But it did mean I didn't have to buy two bikes throughout that process.
I take Dangers point but if your kid falls in the the description above I wouldn't have a problem with extended links. But if he's a real rider, pushing himself and the bike, you owe it, to him, to buy a bike that fits him properly anyway, as Danger suggests!!

[trumpy]

Thanks for the warning Danger but they where on the KX85 we had. The extended dogbones where in when he was learning, so no hard riding/jumping to push the suspension to anywhere near its max. And I looked at all the issues you suggested B4 installing the dogbones, even cut 2" out of the seat as a compromise as well. Wasn't long till he grew into the Factory ones and I'd glued the foam back in and recovered the seat. But it did mean I didn't have to buy two bikes throughout that process.
I take Dangers point but if your kid falls in the the description above I wouldn't have a problem with extended links. But if he's a real rider, pushing himself and the bike, you owe it, to him, to buy a bike that fits him properly anyway, as Danger suggests!!

Totally agree. Once my son got quicker he could also cope with the extra height and the longer dogbones were removed. It just meant that, since we only had to buy one bike instead of two over a given period, he got to own a six month old one instead of two dungers.

[clmintie]

Be aware that these so called lowering links have no effect on the over all travel of the shock. So for a full size bike (for ease of discussion) that has a full 300mm of travel all you are doing is moving the start and end swing arm position. You still have a full 300mm of travel. You don't have to look at the underside of the rear guards of too many bikes to realise that safety margins are already tight. If using a lowering link I hope you don't sit down too much because you could end up removing a Michelin from your rear passage. There have been cases of the rear wheel slamming into the rear guard resulting in spectacular ejections. Same deal with sliding the forks too far in the triple clamps. Most bike manuals recommend 10mm only. If exceeding this you need to remove the springs and run the forks through the full travel on the bike to check that the front wheel does not bottom on the underside of the guard, the pipe or the frame. You also need to consider the effects of different tires and perhaps mud build up if safety is a priority.
There are certainly shops that will sell you and fit these. Your safety is not their priority and I know of a shop that has fitted these to a bike recently, but the owner is going to have the job done properly in the next few weeks and the link is going in the garbage as I refuse to have anything to do with a bike that has one of these fitted.

Most bikes can be lowered internally and need to be looked at in a case by case basis, using spacers and in some cases shorter springs. If your concerned about only 10mm its probably best to wait a month or two for the little one to grow that much and if hes on tip toes its not far off. Or perhaps look at lowering the sub frame seat etc.

Reckless if you value your boys safety please remove the spring from the rear shock, refit the shock and check for travel issues. Factor in the last inch or two of compression on the bottom out bumper. This is an important part of the rear shock and controls the last few inches on all shocks and is meant to compress to almost nothing.

You are correct Danger...

This is our KX85's front mudguard, bearing the resultant skidmark from the combined efforts of Grace getting faster and Dad too slow to drop the forks. She says it was a nasty feeling, involving a heavy thud and deceleration

[speedpro]

I've done exactly this on the KX80 I bought for my son. I made some new slightly longer dogbones and lowered the triple clamps on the forks. I had to put a small scallop into the handlebars to allow the forks to slide past them. End result was a KX80 that was 75mm lower than stock and was just fine with a just starting out boy on it, or even his Dad. Neither of us was doing anything outrageous on it. The dogbones were steel strap the same thickness as the originals and were not a whole lot longer to achieve the lowering amount required.

[paturoa]

On my sprogs KX80 I've lowered the front forks so that there is 37 mm of fork above the top of the top clamp and wound the rear shock adjuster as far as it will go. This has left about 850 mm static seat heigh (not sitting on the bike) and a whole lot less so she can get both feet on the ground. No problems with bottoming yet as not very adventurous. I will keep an eye on it.

[Reckless]

You are correct Danger...

This is our KX85's front mudguard, baring the resultant skidmark from the combined efforts of Grace getting faster and Dad too slow to drop the forks. She says it was a nasty feeling, involving a heavy thud and deceleration

I think we all better still heed the warnings of Danger and Climintie though! And be careful when the suspension is altered! Keep a good eye on the kids progress and make sure they have the correct tool for the job. After all the mods are so easy to alter back to standard and we don't want hurt kids just to save a dollar or two. If they are doing race meetings or starting to come off jumps reasonably well its time to go back to standard or get a bike that is right for the job.

[FROSTY:Me]

Im hearing you guys here. Danger The lad is either flatfoot one side and tip toe the other OR hes up on the balls of his feet.
The buggers growing like a weed.
Is there a "safe" amount that a bike can be lowered from stock?

[Danger]

Any shock can be lowered safely for not much more than the cost of a service by limiting its extension. Some bikes actually benefit from having the rear lowered a little for geometry purposes or to change the starting rate of the linkage (KTM's and some full size KX's).
If your talking safely by the use of lowering links and you don't want to spend money on servicing the shock that's something that you have to investigate for yourself by removing the shock spring and running it through the stroke to full travel and allow for the bottom out bumper to compress beyond where you can push it. Weigh up the cost of the links or time making them and the risk to your childs safety for yourself.
Some forks require shorter springs if available or existing springs can be shortened but this makes them stiffer (sometimes a good thing or we can start with a softer spring and shorten it to get the rate we want). Some have preload spacers that can be removed or shortened and travel limiting spacers inserted. Each application is a little different as to what is required and the balance from front to rear needs to be worked out. I don't get enough of the little bikes in to be totally familiar with what is needed on your bikes front end. Limiting the extension of the suspension lowers the bike and shortens the available travel without the risk of a bottoming under the guard or against the pipe or frame.
Give RT a call I'm sure he will put you right.

[FROSTY:Me]

ok danger--I diddnt think at his level of experience that it would be an issue. -so how much to do the shock bit?

[camchain]

Interesting thread. Just a thought here - wouldn't adding a second rubber bottoming stop (suitably measured/shortened) to the shock shaft, prevent the tire-on-guard bite with these lowering links?

Possibly a 'mickey mouse' idea, but then again maybe safe enough and an alternative to modifying shock internals?

A Michelin based back passage gouging certainly sounds like something to avoid, you might end up with a non-luxury exhaust.

[FROSTY:Me]

ok thanks again folks for all the advice. Thanks to the generosity of Oldguy all I can say is F$#$# lowering the bike for this fella.
He spent all day yesterday tossing a DRZ125 around with no issues at all
He crashed once at the end of the day but in all honesty it was due to a slow leak in the tyre rather than his riding