Gusseting 85 250r frame

[barnett468]

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ok, the white is one version of the "BFP" gusset i was trying to explain . . the lightening holes were added at no extra charge.




This is what the gusset would look like if you painted it with the wrong shade of red.




Here's the TCP gargauntuan model.

[El Camexican]

You may want to keep the following in mind before starting to weld:
- It's always easier to copy something that is already track tested (i.e. the Hall's machine)
- Welding thick things to thin things (i,e, 5/16" plate to 16ga. tube) makes thin things prone to cracking due to them cooling much faster than the thicker material
- Adding 20 pounds of metal to your frame will slow it down and change the way your suspension works
- A frame should have some flex

Good luck!

[atc300r]

I don't plan on adding 20 pounds to the frame just beefing up a couple areas. I know a guy on a trx site that makes and sell gusset kit for the trx. Im going to contact him and see if he will make me a set for the areas on the trx frame that are similar to the atc frame like the footpeg area and rear subframe area. and swingarm pivot. the rest I will go by some of the suggestions by Jason Hall, Barnett. Thanks again for the input guys.

[onformula1]

They are pretty easy to make, just make yourself up some templates, then keep them in a folder in case you need them for another trike or loan them to a buddy.

[barnett468]

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I don't plan on adding 20 pounds to the frame just beefing up a couple areas.

I know a guy on a trx site that makes and sell gusset kit for the trx. Im going to contact him and see if he will make me a set for the areas on the trx frame that are similar to the atc frame like the footpeg area and rear subframe area. and swingarm pivot. the rest I will go by some of the suggestions by Jason Hall, Barnett. Thanks again for the input guys.

ADDITIONAL WEIGHT FROM GUSSETS

Yeah, even if you added all the gussets I posted AND the ones Jason Hall used AND the gussets in the TRX kit in the areas not covered by mine or Jasons, you still wouldn't even have 10 lbs in gussets and welds.


FRAME CRACKS

As I mentioned earlier, although adding gussets transfers some force to a different area on the frame, you will not have an instantaneous catastrophic failure by adding them, and as others have mentioned, in general, it is better to pre-empt a potential problem by adding them to known weak areas on a suspect frame or one of unknown history than it is to simply pray that it won't break in half off that 20' jump at 50 mph smashing the frame AND you into the ground . . Again, simply periodically look for small cracks, and believe me, a portable fold up magnifying glass is a big help . . Some of them also have a light which is even better.


350X GUSSETS

It seems that you are committed to do this, so as others and I have suggested, maybe give Jason a call or pm and ask him what he thinks if you want . . Also, if you want, ask him to look at my ideas and offer his opinions on them if he wants to get that far into it . . I'm certainly not going to cry if he says they suck, lol, I just want you to achieve whatever your goal is with this.


USING TRX GUSSETS ON A 350X

I don't really have an opinion on this, and a 4 wheeled TRX is definitely a bit different than a 3 wheeled 350X anyway, but one thing to keep in mind is the thickness of some of the TRX gussets . . If some are 1/8" thick or less, you might want to use slightly thicker ones like 3/16" in some areas.


CHROMOLY VS MILD STEEL FOR GUSSETS

Even though chromoly is stronger than mild steel, mild steel will be fine in this app . . I would suggest you use chromoly if you ca get it easily and affordably, otherwise just use mild steel.


GUSSET FITMENT

It is not necessary to make the gussets fit into a "corner" where two tubes converge/intersect . . It won't do much to increase strength or reduce cracking in that area and is occasionally a pita, which are some of the reasons I suggested you cut a little of the corner off of them and showed that in most of my images . . Unfortunately I forgot to do this on the image of the rear upright frame gusset on the top.


TEMPLATE MAKING

The manila folders I suggested for doing this earlier will work fine, however, if you make the rear mounted gusset for the rear frame the way I showed it, construction paper might work better due to the size and bend in the gusset, and you could make that gusset with one piece instead of two this way if you wanted to.


FRONT DOWN TUBE GUSSET/REINFORCEMENT

I thought this over a bit, and my previous suggestion was one of two that I was going to make, and after thinking about it some more, I would use something a bit thinner on the front than the 5/16" thick piece . . This has nothing to do with welding thick metal to thin metal since doing this is easy if one is an experienced welder as I'm guessing you know, and we did it a zillion times at Kawi for various reasons.

I'm thinking that even though the 5/16" thick piece I suggested will reduce twisting and side flex more than a thinner piece, increasing the tensile strength is a bit more important, and sacrificing a bit of strength in the twisting and side deflection area won't be a big deal since the strength in those areas will still be increased if a plate of almost any thickness is installed . . For his reason alone, I think that for your particular app you should consider using a piece that is 3/6" thick instead, plus it might not look as out of place, and it imo, it is also important to not look tacky.

It's quite likely that they make metal in a width that is close enough to the width of the down tube that you won't have to cut it to width.


REINFORCING THE SWINGARM PIVOT BRACKET

This is nothing new and was first done in the '80's on some high perf street bikes but was first done on a dirt bike by Kawasaki way back in 1990 when they boxed it in . . This can be seen in the photos of the 1990 KX 250 below.


FRAME FLEX AND "UNIFORM FLEXIBILITY"

This is a complicated and fairly lengthy subject, and I am NOT a foremost authority on, however, I do have a reasonable amount of experience in this area and it is one of the things I was involved with at Kawi.

The more rigid a chassis and suspension are, the more stable the vehicle will be, but the firmer/harsher the ride can become.

The degree of "flex" a vehicle will have is figured in when designing a vehicle, and is mainly dependent upon the intended use and price point of the vehicle . . The stiffer a chassis and suspension are, the more it costs to produce, and it's not practical to design a super rigid chassis for a non racing bike because it is unnecessary and will also increase the cost to a point where its excessive for cost conscious buyers compared to other vehicles.

If you have ever owned a pre 1980's model long bed truck, and looked at the bed in the rear view mirror when entering a sloped driveway, you will have seen it move independently of the truck by so much that you might think the frame is broken if it was the first time you drove one, lol.

Reducing the flex in one part like the forks or swingam will exaggerate/increase the amount of flex in the non reinforced parts like the frame . . This was a major issue I had to consider and deal with when re-engineering the original 1986 Tecate prototype because it was so "flexy" at higher speeds and under high loads it was actually scary to ride.

The reason it was like this is because it was designed by someone in Japan other than the original designer whom really had little idea what he was doing and was unaware of just how hard these things were ridden in the US . . This was complicated by the fact that instead of using the only rider they had that was qualified to ride it fairly hard, they used a guy that would probably be a middle of the road novice in the US . . One of the things it originally had on it was basically an '85 front end and tire.

Anyway, whether one thinks it's good or a bad thing, the Tecate is the most rigid factory produced 3 wheeler ever made, which is partially evidenced by the massive forks and massive aluminum swingarm . . Keep in mind, this is still basically a "recreational" bike.

Many current vehicles like MX and high perf street bikes are now far more rigid than they used to be, and this trend started in the mid 80's with a few different mfg's which culminated in 1990 with the use of a chromoly twin spar frame on the KX 250 which most other mfg's eventually emulated, and which I know was not designed with flexibility in mind . . That bike also had basically flex free 41 mm forks and a fairly low flex swingarm . . In 1990, Jeff Ward won 4 of the outdoor National races but just missed winning the Championship because of a problem in one race where he ended up 13th.

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[barnett468]

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Here's a cheesy image of the proposed half tube supports for the back bone . . There is one long one on top and a short one on the bottom that welds to the bottom gusset and the frame and the top half tube.

If it were mine, I would probably carefully cut the rear tank mount off the top of the tube, then grind those welds flat, then extend the top half tube all the way to where the existing top gusset is and weld it to that gusset, not to the frame, then maybe weld it to the the side tubes if possible, but better yet, or in addition, put a small 3/16" thick "L" bracket the width of the side tubes and long enough to extend 1" onto the side tubes and back bone, then weld it to the side tubes and the existing lower gusset ad the new top half tube . . It looks like it should overlap both tubes by around 3/8" which is enough . . Once you weld the L bracket to the side tubes, put a medium size tack weld on the front edge where it meets the upper half tube and lower gusset, then then whack it with a 3 lb hammar to make it conform to the curved shape of those parts.

You can smooth some of the bigger weld lumps down in this area if needed to get the half tube close enough to weld to the top gusset and side tubes, and you will need to shape the end of the half tube a little to make it fit . .

I'm hoping that what I'm saying will be self explanatory when you look at your frame.

Also, the front of the top half tube doesn't need to go all the way to the steering head if you don't want it to because the back bone has the big gusset on the bottom . . You could stop it around 6" before the steering head if you want so you won't see it at all.

[barnett468]

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I'll post some better more accurate images tomorrow.

[atc300r]

Wow its been almost a year since I started this thread. Havent given up I concentrated on TT racing this year plus some home repairs. I received some parts in the past few weeks. Im going to post a want ad in the classifieds for some more parts I need. Iv got about 90 percent of what I need from friends, 3ww,the 2 trx250r sites and craigslist. There is a new MX track opening within 20 minutes from my home. High Voltage Hills mx Grieg ny. I went to open practice this past Sunday and raced with Greg Huntley and his wife Missy and friend Cory. There were four trikes and about 4-5 quads we all raced together. Today received these.

[hadudj]

Hi,

This is my first post on the forum. I bought a 250R and I'm going to race it in the Norra 500 next year. I bought the inverted forks and I'm in the process of having them shortened. Also picked up a BVC triple clamp. Today I was told this setup is extremely hard on the bike and now I'm likely going to crack my frame. Is a gusset job really required for this race. I'm not going to be jumping and I think the goal is to not beat the piss out of the bike so you can finish the race. Any thoughts on this? Also, being a bit new I'm not sure how to get a hold of this Jason Hall guy, how can I get his number?

Thanks,
Doug

[oldskool83]

every trike and atv frame should be gusseted. I think there is a bunch of guys who sell 250r gusset kits on ebay. Most times its around your shock mounts, sub frame and swingarm areas, plus the up front frame where the go from 1 to 2 down from the neck.

[Dirtcrasher]

Hi,

This is my first post on the forum. I bought a 250R and I'm going to race it in the Norra 500 next year. I bought the inverted forks and I'm in the process of having them shortened. Also picked up a BVC triple clamp. Today I was told this setup is extremely hard on the bike and now I'm likely going to crack my frame. Is a gusset job really required for this race. I'm not going to be jumping and I think the goal is to not beat the piss out of the bike so you can finish the race. Any thoughts on this? Also, being a bit new I'm not sure how to get a hold of this Jason Hall guy, how can I get his number?

Thanks,
Doug

They're just gussets, you can find pictures in Google images and make them yourself if you have time rather than money.

I've been gusseting frames for a long time, but shipping anything let alone a frame is getting expensive. Just use some carboard from a cereal box and design your own. You don't need a plasma table/laser or water jet, just some 3/32 and 1/8th steel, a way to cut it and a mig welder.