Inside the GasGas Pro Cases - Fixing Noise-Vibration

I bought a 2011 Raga 300 that had above-average engine vibration and engine noise. The bike worked fine but not as sweet as my 2010 TXT-motor, aluminum center cases 280 Econo. The vibration is hard to describe, so here's a very short video of the noise when running, and also killing the motor - in slow motion. Click on the photo thumbnail to go to the video. You'll hear the above-normal vibration when revved. Pay close attention to the T-T-T-T noise in time with compression when the engine shuts off.

The T-T-T-T noise is consistent with excessive radial play in a main bearing, which I detail below. Some added vibration may be coming from this crank crank being sub optimally balanced (I later found the crank and flywheel are very well balanced). I'll concentrate on what I know is not as it should be... one of the two main bearings.



Tearing into the bottom end I discovered the right main bearing to be undamaged, smooth rolling, but having excessive lateral play (and thus some radial play). In contrast, the same part, the left main bearing is much tighter. I could not get no more than a very tiny bit of visual lateral play out of it, whereas a video following will show lots of lateral play from the right bearing. (Update on this. I found the lateral play to be normal - see a later post. I found some bearing race wear from grit, and as a result am replacing both bearings to be sure).

There are many custom features of the Pro engine design. Fascinating and admirable stuff to a mechanical engineer! The transmission is a wonder of integrated design. Four gear sets for six speeds and things like the shift drum rotates around the shift shaft. This is a super compact design!

The main bearing design is custom to GasGas and also smart. The design lubricates both bearings, which ar ethe same bearing, both sides, from the transmission lubricant, not from the premix. This protects the main bearings from anything that may pass through the air filter on bikes whose bearings are lubricated via the fuel. A custom feature of the GasGas main bearings is an extended races on one side of the balls for the pressure seals, which run on the inner race and face inward toward the crank. This allows sealing on the inside without a larger seal pressed over the top of the bearing and into the cases.

The left or magneto-side bearing has a conventional additional outer oil seal pressed into the case. Left bearing lubrication is trapped between the seals and lubrication is supplied from two holes drilled to the transmission cavity. There's an oil splash trap on the upper hole. When the gears are turning there is a flow from the upper hole and back to the lower hole. Otherwise oil just stands in the bearing cavity. The right bearing has only the one integrated pressure seal and the bearing balls are open toward the outside, lubricated by the transmission oil from the primary cavity (the clutch side).

The Pro engine is super easy to disassemble as there are no hard press fits anywhere. The bearings have an O-rings in the inner race to seal on the crank, and an o-ring in the case to seal the outer race from the cases. I didn't have to beat or press the crank out of the cases... it just slipped out under a little pressure. Nice!

Here are a couple of pix of the main bearing in the right center case, then the left center case:






Here is the left main bearing from the inside:



The feel test for main bearings is simple. You grab the inner race and force lateral play. The integrated pressure seal impinging on the inner race damps out movement a bit, but it's pretty obvious when you have a sloppy bearing. The identical bearing on the left was very tight feeling. Here is a video of the lateral play in the right main bearing:



(update: I was wrong about this. When I received my new bearing, and examined all the bearings with no seals, I found the later play or tilt to be .011"-.013" on all the bearings. The radial play was very hard to measure, but it was near zero for all).

Moto - Fantastic photos and info on the crank bearings. I tried to listen to the audio of the motor and didnt hear anything. It appears to be a video in a video or slideshow. maybe pull it out on its own? Would be cool to hear.

I hope you continue this thread with more info on what you did to resolve your loose and tight bearing issues as well as maybe your process of balancing the crank (I assume your headed there from comments in another thread)

Thanks for sharing this with us.

Bene that sounds terrible. Did you notice in the video that an air leak seems to appear at the base gasket. It is so short I could not tell for sure.

Hey this took me about 10 edits to get right(er) after first posting, so you all probably saw a less refined posting with the messed up video. I fixed the video and the post should be much better now.

No air leak. Notice an air leak from a few seconds of low-rez video? :eek1

The Raga has both a 300 and a 280 top end on it for fun experimentation. Zero air leak issues. I posted the results of that in a word doc earlier under (got to go find the title).

To clarify: It's only a bit more 'terrible' than normal, and digital cameras accentuate high frequency noises. It worked fine as was, but I'm a strange fellow who is hyper sensitive to machines, like some 'moto whisperer.' Motobene in Italian means 'motorcycle good.'

Had I not had that very sweet TXT motor between my legs for more than a year, I might have written the noise and vibration off as normal to this design because, while it may be irritating, it has not horrible. This bike is famous in these parts for being a great runner, like a jacked up race horse. My aim is this exploration it to also make it a very sweet runner... smoother and more quiet.

Working now - thanks! I see what Lineaway was talking about - but think that is probably just a video compression artifact. Either that or we call Motobene - MotoBrutto..

Boy that does sound bad - sounds like your ratcheting Stings wetbike onto a trailer at the end.....Im sure it sounds different in person, but my total guess would be a chip on the idler or helical gear. My bet is this sounds different in person or my cheap speakers are shot. Given you have the engine apart - maybe worth a glance or two.

Great write-up and info, thanks!

What is your opinion of and experience with the tranny design with respect to durability/longevity? I would prefer to have the easier to register GG (and the narrower motor), but was reluctant to commit due to a few reports of failures related to the 4-5 shift. Reports overblown? Nothing to worry about with careful shifting?

(will be trials riding with it, not trail riding)

thanks

All design is a compromise. I happen to ride a GasGas. I avoid brand worship or brand bashing. Allow me a bit of brand defense, however.

Stoodley rightly describes the Pro motor design as a brilliant and a little more delicate. "Take some care and you'll not have problems", he says. Could the shifter stomping abusive types have more problems with this design? It's possible, but all the brands have gone toward lighter and more spindly to stay competitive.

I hear of concerns about the transmission, but I don't have concerns. The Pro is now long running and one of the most successful trials bike designs ever. Had there been too many problems over too many years, and no steady improvements, there would have been market rejection. GasGas absolutely dominates my area, so there are a lot of them to observe. I don't see unusual failure rates, or even failures.

The shifting of the 4/6 tranny in two of the 6 gears feels a bit different sometimes, but it doesn't detract from winning events. When adjusted right the tranny shifts smoothly and you'll notice 1st and 4th I think it is being different ever now and then, but it won't keep you from winning events. If not adjusted right the Pro will shift balky and you will notice that. Adjusting - should that be needed- takes about 15 minutes.

Looking at durability more deeply there is a significant human factor often overlooked. I mentioned it in the second paragraph. When I worked many years in lower-limb prosthetics design and manufacturing, we had people who would destroy our feet and all the other brands too. Some would wear out stuff faster, even if their activity level was not that high. I puzzled over this a long time. How could I be a 99th percentile amputee athlete and yet not trash prototypes and production feet as fast? I came to understand the variable of machine awareness, or lack thereof.

Machine-aware people work with machines, whereas machine-unaware people are oblivious to machines and work against them. This is how a teenage girl can burn her car's clutch out in 30,000 miles, whereas the machine aware driver will never burn up a clutch. If a machine unaware rider is concerned about durability, there always the TL125 or TY350

And then poop happens. You can be machine savvy and crash wrong and break something on any brand. Or just have a bad part to start with. No fault of yours. Fortunately quality control of Euro brands has vastly improved over the last 20 years. Trials bikes are generally easy to work on when feces does take place.

I chose brands and models based on my preferences, needs, and bike availability. I ignore fears about designs unless there is huge and obvious problem. Regarding the Pro transmission, there is no huge and obvious problem.

How did the kick start gear look. I`ve seen a 1 month old bike sound like that by just a small piece traveling to the primary gear. It was so small I could not find it. Finally went tooth by tooth with a magnifier before it was found.

Thanks. Kick start gear looks pretty good. The primary gears look good too, but those and the kick start idler gear will have close inspection just to make sure a gear dent isn't an additional variable.

I heard that in earlier models a piece of something could break off and travel through gears before settling to the bottom. What year model was the bike with the dented gear?

Thanks. I have fun with this stuff.

The crank balance issue on the 2011 has been perturbed - or perhaps explained - by the loose right bearing. (Update: Wrong about this. Both bearings may have just enough wear to be the cause of the problem. Both will be replaced).

The knock out punch for crank balance and bearing tightness on the 2011 will come when I put the 2009 TXT crank, which I know for sure is very well balanced, into the 2011 with a new crank bearing. (Update: The swap of crank and flywheel had the Econo running as smoothly as ever. The problem is not due to sloppiness in crank or flywheel balancing).

The only other variable that might account for more imbalance in the 2011 than the 2009 that I can think of would be the lower modulus of elasticity (stiffness) of the Raga's magnesium cases versus the TXT's aluminum cases. Riders with the pretty red 2013 Race models, if it is true that aluminum cases were used in instead of magnesium cases as was the case in `12, should rejoice in stronger and stiffer cases! I heard a rumor that Raga uses aluminum cases. He may need the increased strength and stiffness of the aluminum cases. (Update: This has not yet been tested)

I've weighed the Raga bottom end. When I pull the TXT bottom end I'll weight that too and be able to report what the weight difference really is. I suspect it won't be much at all. (Update: the difference was +1 kg with aluminum cases).

I want to say an `07 as this person bought a new gasser every year. Even though Dale has had to warranty something most years. ( His `08 Raga I replaced the frame.) But Dale has always taken care of all issues.

Motobene you make some interesting points. I like the term "machine awareness".
I just wonder, do the riders of any other brand Trials bikes feel the need to defend the reputation of their gearboxes?

That makes sense. That was about the model year I heard the piece could break off.

The elipical tube frame (or was it an early round-tube frame) did have some issues. I had an older 2008 frame on my Econo and liked it for being compact between the calves. I bang into the seat plastic a lot on my Raga.

All design is a tradeoff.

I dont think there was a "dented" gear year. I think there was a bad pawl heat treat "batch" around 07-08 as I recall. I broke my 08 pawl, but It was my fault. As you may know, There has been several changes to the kick start shaft, stop and pawl to help reduce the likely hood of gear clash that causes chips. The 11 has all the updates sans the new replaceable shift shaft design. (real nice feature) Regardless, its still possible to chip the pawl or idler gear if one doesn't use the proper kicking technique. One slap is all it takes. The chips on the idler typically end up behind the clutch hub and into the primary/helical gear. A variety of crazy noises can be emitted, but they typically have a very "metallic" buzz to them. I have always replaced the idler if Ive found damage, and will lightly file any burrs, but know several GG riders who just ride them and the noise eventually goes away with wear. I would be too uncomfortable with that approach, but some are just fine with it.

I`ve heard strange noises coming out of the pro`s over the years. The one I`m talking about had a tick, tick, just like a rod starting to knock.:eek1

Good to hear, I suspected as much but didn't come across the right bike at the right time. Thanks much for the comprehensive answer. (which I expected after reading your rear shock rebuild response) ;-)

Re brand worship, I try to get different colors, as it makes it easier to convince my wife that each is very different and that I NEED the next one. cheers

We jokingly give gassers the label `Pro-blems` for assorted issues. But when everything is right the power is better and the bike is very light! Hard combo to beat if you have to hop all day.