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S3 Low Compression Head Replacement


Robinhobbin
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There is no one modification that will make the bike easier/tamer to ride. They all make an improvement to ride ability. I would start with the cheapest and easiest, slow throttle, gear it down one on the countershaft. Low compression head makes it easier to start and less drama with fuel, larger base gasket is also a cheap mod and the flywheel weight also helps. A mate of mine who was having difficulty in transitioning from a 325 Bultaco to a 250 gasgas and having to get used to using the clutch eventually did the mods and the bike was so easy to ride, very predictable and still plenty of top end for the sections he was riding.

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Thanks Sherpa325! That’s exactly what I need. I’m actually having a very hard time ordering the parts though. I can get a new front cog but not the spacers or gaskets. I’m in the U.S. and can’t find suppliers. Some British shops advertise they have them but so far all are out of stock. I’ll keep trying. At least I have a plan to move forward with that shouldn’t break the bank. Thanks again!

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Here are some USA online dealers, not sure how much 2023 items they will have in stock.

https://trialssuperstore.com/

https://www.tryalsshop.com/

https://www.trialstoreusa.com/

https://factoryonemotorsports.com/shop-by-manufacturer/

https://lewisportusa.com/

GasGas.com search for USA dealers, Brick and Mortar stores.

https://www.gasgas.com/en-us/dealer-search.html

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16 hours ago, konrad said:

My experience has been that you can get the newer GasGas trials parts in the US via KTM dealers (often at a discount).   But you may have to come up with the part number on your own.

this should help with that - Credit: The Hell Team in Australia - https://www.thehellteam.com/technical-support/gas-gas-parts-and-service-manuals

https://drive.google.com/drive/folders/1DGheDNbhzVPDilvBpBIbRDkkqtXsKuXr

Edited by zippy
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I had very nearly the same experience with my brand new 2023 txt300 Racing.  It was just too snappy and fast for backyard plonking around at my novice experience level. I whiskey-throttled and crashed a few times and genuinely feared I'd end up hospitalized.  I didn't want to constantly ride the clutch, so I got a tooth smaller countershaft sprocket and a 10 tooth larger rear.  ((I needed to buy a new longer chain)) The bike is still snappy, but it's much slower.  I can ride at a walking pace without the clutch and if I do grab too much throttle, the bike will wheelie, but I'm not falling/flying off the bike at 25 mph anymore.   No doubt, a more skilled rider could ride the bike as-delivered and have no problems, but I could not, and I wanted to survive my newbie phase.  Lol.

As for starting: Thanks to this forum, I learned this technique:   Put the bike in second gear.  Roll it backwards without the clutch til you feel heavy resistance.  A few inches is all it takes.  You're now at BOTTOM dead center.  Hold in the clutch  and give the bike a kick. It'll be much much easier. My bike usually takes 2 kicks to start.  My leg isn't sore, I'm not exhausted/frustrated, and I'm enjoying my bike and not feeling like a dumba$$ who bought a bike I can't start or ride.  Lol

I also got the slow throttle tube, but I can't say it helped tremendously, although for a more nuanced rider, it probably makes a difference.

I also bought a low compression head. But I haven't installed it, because I think the gearing change and BDC starting technique are working for me 

Good luck and heal fast!

Edited by Scottro
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Thanks Scottro! Reading your experience was just like reliving mine. I’ve installed a slow throttle with minimal change if any but my next step is a low compression insert. If that doesn’t work I’m going for a flywheel weight. If I’m still unconvinced after all that I’m  hanging sprockets and buying a longer chain like you. Thanks for your well wishes and stay safe yourself. Best of luck!

On 11/22/2023 at 10:02 AM, mcman56 said:

"bounced me backwards just a bit pulling on the throttle."

That is exactly what I would describe as the throttle getting away from you.  In that situation, a smaller front sprocket makes the bike run out of RPMs quicker so it can sort of choke off or minimize the "getting away from you".  It is cheap and easy to try.

 

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Sounds like a plan. Something to keep in mind is a rear sprocket and chain is about $100-120.  The low compression head and flywheel weight is closer to $300-400.  I had the head in-hand, but figured the sprocket and chain was worth trying first since it was a less invasive change.    I like the throttle response, I just didn't want the speed.  I can catch a looped bike at 5-10 mph.  At 15-25, I'm done for.  Lol

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You can get a 9 tooth front sprocket, not sure whether yours would have a 10 or 11 as standard. As I said before there is not one modification that that will magically make the bike super easy to ride. These bikes are meant to be ridden on the clutch all the time and riders that are new to this style really do struggle to adapt. You have to learn to cover the clutch with one finger at all times, in other words you never ride the bike without your finger on the clutch. As soon as you start to get out of control you pull the clutch in and moderate the power going to the back wheel, it does take some time to adapt, but once you do you'll feel much more comfortable.

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Thanks, I’m planning on several changes including a 9t front sprocket (maybe rear too), slower throttle, low compression insert and my finger on the clutch. If all else fails I’ll add a flywheel weight. I’m doing one thing at a time to save money and to see what each mod does to my bike. I got a lot of great advice here. Thanks to all!

I’ll return with how things work out. It might not be until spring tho because the weather’s very cold and rainy now. Everything is just mud.

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  • 1 month later...

Just wanted to follow up and let you know I’ve got my bike sorted out from suggestions posted here by all of you. 1st: I installed a slow throttle with very little success. 2nd: I installed a head spacer to lower the compression to make starting easier and mellow out the throttle response to a more smooth and predictable way. It worked like a charm and cost hardly anything; about $25. 3rd: I added a flywheel weight to keep the RPMs from getting away from me and racing off without me. Again, worked like a charm. Lastly, I will keep a finger on the throttle. Also, I want to thank everyone who was so helpful and pitched in to help me solve this without breaking the bank.

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