GPX……What have I been doing to this poor thing?

I was recently asked what I’ve been doing to have some of the issues I’ve seen. Much is likely self inflicted, I’ve got some riding friends who say I put some hurt on my bikes. I don’t 100% agree, but what yah gonna do. My reply to the question was asked follows ….
I’ve used it the same way I used my KTM 350 for nearly 4 years. Except in 4 years, 200 hours and 6000+ miles (including far more racing and street use), the KTM didn’t have a single issue this thing has had in under 30 hours of use. I’ve personally ridden the TSE offroad 3 times. I know Navin put however many hours on it before I got it, but still nowhere near the accumulated hours on my last bike.

First time, I put maybe 45 minutes on the bike before the rear fender assembly exploded due to caked on mud and me riding a very intermediate MX track with a license plate on the bike.

Second time, the bike randomly stalled on me on a moderately aggressive MX track, I assume my bad for somehow getting gunk in the carb. Fork seals also went that day and I should note that even at this stage my front brake was already inconsistent. I had one crash here on an endurocross tire when I lost arm strength and momentum and tipped over, though I don’t recall it hitting the side, and I don’t recall (or see in any of my pictures) of a failed subframe at this stage. I’ll go through my reference pictures to see if something pops up.

Third time, you can watch the video because it was my race. I noted earlier at what time the shifter gave up the ghost. If you want, you can watch before that and see if I did something. Maybe I looked at it wrong, or attempted to shift too quickly, I don’t know. Things you don’t think about when you’re racing, and in the past 8 years of racing, not once ever thought about. There’s the brake issues as well, though as I’ve been perfectly open about, the failing fork seal likely attributed to my lack of front brake feel, but the rears were inexcusable.

I got the messages from GPX regarding the plastics. I was curious on their cost as yeah I had saw that the OEM Husky stuff comes in at a heft 440$ (with new associated hardware). A tough and bitter pill to swallow on a bike that is rapidly & continually pushing North. My issue with the GPX stock parts is what I’ve noted before. The manufacturer may have copied the Husqvarna stuff, but they skipped over the critical details, which to me are make or break. Every single threaded insert on the GPX appears as though it is a round turned part, presumably with knurling. Many threads so far have seemed undersized (causing bolts to get stuck in them), and my personal guess is that they are not molded in, but likely heat staked in post-molding. I can’t confirm 100%, but given that many are in blind hole areas, overmolding that can be tricky. Doable, but tricky. Why they didn’t use hex stock, or add some sort of undercut detail to help retain the threaded inserts, I don’t know (related to whether or not they’re molded in vs heat staked). I have my assumption.

Threaded inserts aside, you then have the exact material makeup. I assure you that as many metals you know about, there are 10x as many plastics. Each plastic just like metals can have different flexes, rigidity, slip, all that stuff. I can’t say on the subframe how it matches to the OEM Husqvarna parts, but with absolute certainty the material used for the fenders is different. Not only is it different, but key areas where they should have molded in pieces of aluminum for added strength was not done. Again, I assume to hit a price point and the possibility of not understanding the importance of these things.

I’m appreciative of the fact that GPX has these parts in stock and at prices lower than the Husky parts that were copied. Unfortunately as I’m finding (and apparently alone in this), but the low price is proving the old man saying of “buy once, cry once”. As I noted earlier as well, I’m getting to the point of being ready to toss in the towel and admitting that this is not the right bike for me at this time. Unfortunately (for me) GPX has kicked the price of a new 2019 down so low that resale on these is (assuming) sub 4000$ range, given a new one can be had for $4500. Kinda wild considering that the bike was just released less than 6 months ago? It’s sadly putting this closer to the territory of a disposable item. It’s a shame as there was (is) much potential for this.

But like you said, I’m 1 of 700 of these. Maybe I got an oddball, or the first off the line. I don’t know. Maybe I just have crap luck with bikes and needed to perpetuate my Buy High, Sell Low Mantra. Like the Yin\Yang, maybe I’m just on the downside of that.

I’ll be getting this one buttoned back up, and contemplating whether or not I take it to the Brushpoppers event and how I am going to move forward from here on out. As I said above, there is much potential, but for me at this time, it just may not be the right fit.

All that aside, has anyone had any feedback regarding the oil injection pulley not lining up to per the DT230 manual? 3 bolts & a twist of the grip to check. Maybe something changed along the way, but the only thing I have to go off of is the DT230 manual.

An addendum to this is that I still praise the tse suspension. The motor is an absolute pleasure. At the price point these bikes are very hard to beat. I’ve likely had some first run teething issues and some self inflicted problems as noted.

Andrew

GPX repair update 1

[IMG]
Race ECU on the Left – OEM on the Right.

While swapping ECU’s I noticed a bit of an issue.[IMG]

Yup, it seems I managed to crack the right side subframe. No idea how. No idea when.
I suppose this winter I’ll strip it all down and see what I can do. A sharp eye may also note that I no longer have the original self tapping screw holding the CDI down. Why might you ask? Well upon replacing, the plastic completely stripped out where it threads in. Further inspection revealed that the CDI was threaded into 2 very thin areas. Odd, as literally a couple MM away, are 2 hefty self tapping screw holes with solid bosses beneath them. Why these were not used? I don’t know 100%, but it appears the CDI was relocated nearer the fuel tank in order to allow room for the starter solenoid. When I have more time, I’ll investigate further, but I needed to do something to at least hold the CDI in place for the upcoming dual sport.

So since my OEM rear fender broke (right side lower retaining screw, above the exhaust), I ordered a proper Acerbis one, and the difference is night and day. The plastic is more supple, I assume they use either a toughened PP or something added to it to allow a bit more flex\give than the one that came stock. In addition to that, a sharp eye will note that the Acerbis fender has 2 aluminum washer\spacers molded into the fender. The OEM TSE unit did not, and IMO is partly why the fender failed multiple times on me.[IMG]

You may also note that the screw on the top right is not 100% flush. As I was tightening this, the threaded insert in the subframe stripped out on me. I’ll have to work on extracting this later and fix this issue.

The following picture shows how I had to fix the stripped out threaded inserts in the sub-frame. I may look at replacing these with better threaded inserts (we use a LOT of them at our shop that are molded into many various products), but for now, the most straight forward option was the following:[IMG][IMG]

It’s ugly, a bit of a PITA to deal with, but it holds the fender on. So there’s that.

There were some positives, and I did not get any pictures of the engine reassembly. Hands were oily and I didn’t want to muck up my phone.

The new shifter went in smoothly, and once the side cover was on, the difference was immediately noticeable. I had 0 left to right play (grabbing shifter on left side of engine, and push\pull it in\out). It would not move. My old one would shift back and forth quite a bit. My guess is that the original moved too much, allowing the pawl the slip on the star, which then allowed the pawl spring retainer to collide with something and shear itself. It’s my opinion that nothing on the pawl side is what is the “full stop” for the shifter. That is 100% decided by the tangs on the left of the shifter by the main shifter return spring. I failed to get a measurement to compare with original, but a small visual check appeared to have a more narrow gap than my original unit. Whether this was wear, damage, or a dimensional issue from manufacturing, I do not know.

The next thing that popped up to me during reassembly was with regards to the oil pump. Since the lines were pulled, I wanted to get everything bleed correctly. I opened up the DT230 manual and began reviewing. Upon review, I noted the following:upload_2018-10-26_8-50-29.png

To note here, at 100% throttle, the notch (A) should align with the output (B). No matter how much I adjusted the cable, I could not achieve this setting. Has anyone else seen this? I assume since its got a heft amount of hours, it must not be super critical here, but I adjusted as much as I could to get as close to max as possible.

Well, that’s about it for now. GPX did ship a little extra for me, so that was nice. Thanks for the swag & pardon the sweatshirt.

[IMG]

And kudos for it not being a flatbill

TSE250R Shift Issue

During a recent race, I found that when I would attempt to shift from 3rd to 2nd, the bike would sometimes drop into neutral.  I began digging in to understand what was happening.  If you’re a TLDR type, its basically a poorly manufactured shift shaft that has too much slop.  There is the additional possibility that the stop arm on the shift shaft was bent due to use, but I can not say 100% here.

Here is a video of me replicating the issue with the bike on the stand:

Here is where part of the problem lies:
upload_2018-10-18_7-50-10.png

The tab on the left is what stops the shifter from rotating too far down (ie clicking down through gears). Arrow on the right is pointing to where the spring loaded shift pawl is connected to the main shift shaft arm. The first issue is that the tab on the left needs to be rotated in slightly. I’ll have a more accurate measurement later, but this allows the arm to rotate ever so slightly too far down, allowing the detent to slip over into neutral.

This issue is exacerbated by the fact that where the shift pawl interfaces with the shift arm, is extremely sloppy.
[​IMG]

I attempted to make a slow-motion video here:

I believe that adding a bit of weld to the face of the shift shaft like @Jazzy6 will be required. If the “stop boss” on the clutch cover wears enough, or the total slop in everything is too much, the shift pawl could lose contact with the shift star itself. Mine had a little bit of movement (in\out), but not enough to completely lose contact with the shift drum star.

So I’m looking at this a couple ways. One, I can just weld the arm up to stop the movement of the shifter, thereby halting it from skipping past 2nd and into neutral. If I do this, I’d also look at welding a dot on the face to reduce\eliminate the in\out slop of the shaft itself. The other option is I go all in and make a new one. I don’t think I’ll do that, as it just doesn’t seem worth it.

It is interesting to note if you look at the WR200 shift shaft, it looks like this:
upload_2018-10-18_8-13-48.png

I wonder why they didn’t do a full loop over the tangs on this DT230 engine. :dunno If Possible, I may weld an arm connecting the 2. I’ll verify if anything would interfere, but this would insure the arms don’t bend prematurely.

ALso note….. The spring detent is just fine:
[​IMG]

Another tidbit….. If you look at the 5 o’clock in relation to the main gear in this picture, you’ll see a gray looking spot on the smooth surface. That looks to be where either the water or oil pump gear is wearing into the surface of the cases. Not sure if it’s something to be concerned about, but already seeing a worn spot.
[​IMG]

Also to note on my site here is that I found this while working my way in to get access to the shift shaft:

Yes, that’s the nut holding the clutch basket assembly to the motor.  You’ll note that while there is a lock washer in place, it was not set in the “locked” position anywhere.  May be an isolated case, but not exactly what I’d call encouraging.  Far from what I’d be expecting for a bike with less than 40 hours on it.

Andrew

UPDATE:

Based on a discussion on ADVRider, another individual noted he had the same problem over a month ago, which was relayed to GPX.  The issue stems from the tab which holds the pawl spring.  You can plainly see on mine, that it is deformed and close to breaking off.

That should be perpendicular to the main body.  Mine as you can see is close to tearing off (opposite side)

Temporary solution will be to bend & weld this tab.  I will also work on correcting the slop out of the pawl, is it’s quite sloppy.

TSE250R Technical Info

This will be my collection of various technical information.

Engine:

DT230 Service Manual

Suspension:

ARX01RC Fork Rebuild How-To Help PDF

The above PDF may not have 100% accurate information.  Based on some internet feedback, the following oil volumes & weights are acceptable:

Inner Chamber: 2.5w @ 160ml

Outer Chamber: 2.5w @ 250ml

Found this FastAce teardown video on the GPX unofficial Facebook Page.  I’ll add Part 2 when its posted.

TSE250R Initial Ride Report

First of all….What is it?  The TSE250R is the 2 Stroke Big Bike offering from US Based company GPX Moto.  GPX Moto is a subsidiary of USA MotorToys who also owns Pitster Pro (small bikes).  The TSE250R is in essence a Yamaha DT230 motor packaged into a 2017 Husqvarna TC Chassis.  The manufacturer (in China) apparently bought tooling from Yamaha for the engine, and so far as I know or can tell, the frame, plastics, etc are Husky replicas.  GPX opted on this bike to adapt a CRF450 front fender and a 2015 Yamaha WR450F headlight.

Right side look at the TSE250R

After a bit of time in transit, and getting my lights wired up, I finally got to fire up the TSE250R for some test riding.  Keep in mind that the bulk of my riding has been on the street.  I’m in the middle of flatlandia IL, so very few places to actually ride off-road.

Despite most of my riding being street oriented, it gives a little different perspective from others.  Traditional 2 Stroke engines conjure images of vibrations and the tingling feeling in your hands as they’ve been buzzed to oblivion.  The powerplant of the TSE250R goes a long way to address this issue.  The TSE250R engine, initially a Yamaha engine is one that is counterbalanced.  This counterbalancer smooths out engine vibrations to a degree that on the street, you’re feeling more vibration from the knobby tires than the engine itself.

Right side of engine showing expansion chamber and oil injection pump area.

Now this is not to say that the engine does not feel like a 2 Stroke.  In just about every sense, it does.  There is the ring ding ding of the expansion chamber (which is double walled and sound deadened for noise reduction).  The power kicks in with a bit of revs and tapers off smoothly.  The state of tune on this is for overall power spread.  You’re not getting a massive hit with this engine.  Riding on the street really exacerbates this as you feel the revs taper off quick as you’re clicking through the gears.

Stock gearing on the TSE250R is 12/52.  Comparing this to the original Yamaha this motor was in, and this is incredibly short.  Original DT230 bike ran 16/55 gearing.  This variance though shows just how wide and versatile the transmission in this engine is.  With the TSE250R’s oem gearing, you can comfortably cruise on the street at 60mph.  At these revs, the engine is turning a calculated 7000 RPM.  Despite how high these revs are, as noted earlier, the bike is oddly smooth.  Same setup dropped into some light off-roading and the bike immediately feels far more at home.

Stock chain is O-Ring Type

The brakes on the bike appear to be very similar to the Brembos commonly found on KTM and other Euro bike manufacturers.  However the brakes on the GPX are not Brembo.  This is not a major concern though as the brakes feel very positive, have great grab and when asked, will lock up the wheels.  Time will tell on how they hold up, but initial impressions are very positive.

Very KTM like brake and swingarm setup.

My time spent off-road has been minimal, but this is where the TSE250R motor is shining.  The engine pulls in a very linear fashion.  While a big hit of a more racey 2 Stroke may be exhilarating, wider and linear is excellent for off-road.  A quick stab of the clutch quickly picks the engine up onto the pipe, but still smooth, tractable.  In a small ravine, 2nd gear hopped the front wheel over a water eroded rut with ease.  Rolling back down and to jump out, on the gas, the bike roosted out with a slight jump.  Landing and immediately accelerating off to the edge of my property.

A downside to the bike so far has been with regards to throttle and throttle response.  Coming from a Fuel Injected 4T, with an ultra light throttle, I miss the immediate response.  Fuel Injection provides absolutely crisp throttle response.  In comparison, the carburetor dulls these responses and even with “perfect” jetting on a given day, it’ll be slightly off the next.  That is what it is.  I appreciate its simplicity, but if you’ve been spending time on an injected bike, you’ll feel the difference.  The other downfall is the throttle is on the heavy side.  This isn’t carburetor related, but moreso that the bike has mechanical Oil Injection.  For this to function (for those not familiar with 70’s 2 Stroke bikes), the throttle cable splits off in a Y, with one end terminating at the carburetor and the other at the oil injection pump.  The more throttle, the more oil.  Consequently you end up with spring returns in both the carburetor as well as the oil pump, giving a slightly heavier throttle pull.

A side look into the “mikuni TM” carb.  Note also the electronic Powervalve

The main thing I’m anxious to test more on is with regards to suspension and chassis.  The TSE250R is setup with FastAce suspension.  The bit I did test on my property felt very compliant.  Despite running tires at silly high pressure (24psi for road use), the tires kept firmly planted on the ground.  Looking where I wanted to go, the bike didn’t think twice about tipping down into the turn and following through.  Steering is incredibly light with great feel.  Turning radius does feel somewhat limited, though this may only be an issue if you’re going full trials mode with your riding.

I noted the downside above regarding throttle pull, and while I’d like to say that is my only complaint, I feel there are a couple others that can be noted.  One is that there are hints of the “Chinesium” on the bike.  These details can be seen in add-on type areas.  For example, the front fender is off of a modern Honda CRF450R.  The triple clamps appear to be KTM Replicas.  Instead of adjusting tooling for the lower triple clamp to directly mate with the Honda based front fender, they chose to make a steel adapter to fit the Honda fender to the KTM clamp.  Yes, it works, however this adds weight and extra complexity.  This is the same for how other extra parts add on notably around the dash and extra brackets for mounting a number plate vs the supplied headlight.

My greatest real concern on this is the fact that everything so far on the bike appears to be a replica, or I guess say it how you will, a knockoff.  I found this out as myself and others online were beginning to rejet their bikes for use and weather.  The carburetor is supposed to be a Mikuni TM30 carburetor.  After digging in, it is apparent that the carburetor too is a replica of the original Mikuni.  This can cause issues if you’re looking to use OEM Mikuni components.  Main Jets from Mikuni for this carburetor are a very goofy thread size.  M5.3 x 0.9.  The manufacturer of this carb opted to thread the needle jet (where main jet threads into) with the more common M5x0.8.  They also size their jets differently from Mikuni.  Not major issues, but it can throw some complication in the mix.

As things stand, it’s hard to say how you can beat the value of this bike.  New from GPX, the TSE250R hits the bank for $5600 (+Shipping).  Compared to a new KTM, you’re saving around $3000.  Long term is obviously a work in progress and you won’t have to twist my arm to do my part to put this bike through a torture test.  Simply put so far on this is that if you’re OK with being a sort of beta tester for a first line of bikes from GPX, then you very little chance of being disappointed with the bike.  I know I’m looking forward to what else GPX has in the works.

Overall this is a great machine that should be on your new bikes to consider list.

For more pictures and detail views, check the following gallery: