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  1. #1
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    Struggling with my TRX2.5

    (Sorry this is a copy from my thread on the rustler page)

    Hey all, reaching out as Iím struggling with my Rustler. Currently have an OLD 10+ years 2.5 (donít even think itís an ďRĒ just basic 2.5) in it that I cant tune for the life of me. Bought the engine 2nd hand and it not really ran it my self for a number of years until my 3.3 died. So, my problem is the engine will start ok when cold and I can get 1 maybe 2 tanks through it until it starts to bog out and refuses to hold a tune! on full throttle. I wouldnít class my self as a noob at Nitro and originally suspected an air leak so renewed the front bearing, stripped, cleaned and sealed the engine and got no results! When I floor it the engine picks up but then bogs to a snail pace and the sound is like a hollow BARRRRRRRRRRRRR sound if that makes sense. The engine over heats and cuts out and is then is a PAIN to restart until the it cools. I know this is normally a sign of being too lean but the HSN is already 6 1/2 turns out and the LSN is 1 ľ turns past flush so should be ok. If I put this back to factory settings the engine hardly starts and refuses to idol. Ive tried a new plug, and new 20% fuel. Im starting to think this could be worn piston and sleeve, there could be more compression but this still seems ok and the piston cannot be pushed right through the sleeve. Ive tried pinning the fuel tank lid down in case itís a pleasure issue but that doesnít change anything. The engine will rev and accelerate fine when I hold it off the ground but as soon as its down and has to move its self this is where the problems start. Currently have a single chamber Resinator exhaust on too if that could cause any issues?
    ive tried going throught both needles with small increaments, lean and ritch with no lasting improvements. the engine at the HSN 6 1/2 and LSN flush + 1 1/2, idle 1mm will idle fine for 2min+ its only under acceloration when the engine has warmed up i have this problem, Iíve checked the carb and fuel lines for blockages.

    Any help would be appreciated as Iím STUCK and out of ideas.

  2. #2
    RC Qualifier nebulous.cow's Avatar
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    To me it sounds like piston and sleeve are gone. You don't have to run out of "pinch" for it to go bad. You could still be getting blowby, and it will act the same as no more pinch. It's a cheap replacement, especially when you compare it to the cost of the bearings you already replaced and was unnecessary as you said.

    Keep in mind that carbs can leak too, especially when they're a decade old. The parts in carbs (particularly the throttle barrel/slide) rub back and forth their entire life, and eventually leak air themselves. Normally, carbs last at least the engine's "lifetime", but are not non-consumable.

    And lastly, make sure your flywheel is tightened down hard onto the crankshaft. A loose flywheel can cause horribly erratic engine running, power loss, inability to idle, and much more.

    To me buddy, it sounds like you just need a whole new engine. To me, unless it's got sentimental value (which is perfectly reasonable) it's not worth "fixing" this engine. You'd potentially need a new piston/sleeve set, a whole new carb, and maybe a seal set for everything.

    I'd say take advantage of the Traxxas Power-Up program and get a new, discounted engine, or source your own new engine. Nitro motors inherently have relatively short lifespans, because of the insane rpm, heat, and running conditions. If I had a motor doing what yours does, I would get a whole new one. Probably not what you wanted to hear, but it's a simple solution.
    Hope this helps.

    -Mike

  3. #3
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    thanks Mike,

    yeah i had thought carb but theres no knock on the barrel and it feels kind of tight i did a full rebuild and seal on that.

    unfortunatly Traxxas dont offer the powe-up programme (unless someone can correct me) in the UK which is why im currently sat with a .15, Now 2 faulty 2.5s and a 3.3 that wont run. although i think only the 3.3 is less than 5-10 years old. and still running 27mhz TX/RX lol deffo more casual hobby.

    uk price for the parts is about £65/$79 for piston ans sleeve on the 2.5 and around the £80/$97 for the 3.3 ergh!
    new engines start at about £200 for the 2.5.
    i get the bearings direct from a supplier not from Traxxas or model shop and a sealed front bearing is about £2 for stainless steel deffo the way to go.

    its just annoying when my father has some Webra and OS aircraft engines that are close to 40 years old and still on the origional piston and sleeve and run fine.

  4. #4
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    also on that note, Id like to hear from any traxxas employees not sure if any actually read this why they wont offer the POWER-UP offer outside the USA. After been told to contact the UK supplier by Traxxas chat "support" they supplier told me that they have approached the company about this numerous times and been told no each time. What gives? If I’m happy to post the engine(s) to the USA and pay the same as a US customer would why can’t I??? If they are happy for us to buy their products then surely, we should get the same level of support as a US customer. A 2Kg parcel from the US to UK is only $24. Its not a lot to ask for and in this age of globalisation isn’t exactly a hard feet to put in place.

  5. #5
    RC Qualifier nebulous.cow's Avatar
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    I think you're right. It's stupid. There must be a reason, maybe it's customs, or that sending items with "explosive fuel residue" internationally is an issue.

    Bummer too, those prices you mention are not good either. If I was in the UK, I might look at non - US based hobby suppliers too, since you're physically closer to some others.

    Also, you can't quite compare plane engines to car engines. A lot of plane engines, and especially helicopter engines (from my experience as a 3D heli pilot not too long ago) are built entirely different than car nitro engines. They have piston rings. That alone significantly reduces the literal friction and heat generation, and those airplane motors and helicopter engines are massive. My favorite heli engine was 0.96 size. Absolutely a monster. And on top of having rings, they don't spin NEARLY as fast as the small car engines.

    Air nitro engines have way easier lives in my opinion. No dust to get in them, they run at constant high rpm, and thus a nice rich setting to get a lot of oil, and they're bigger and slower.

    Bummer about your engines, and import costs must not be great either. If I was you, I would only buy the best engines money can buy. So that I don't have to buy them again.

    Maybe your Traxxas needs a nice OS from OS Japan.

    Hope this helps.

    -Mike

  6. #6
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    Power up program

    Iím in Toronto, 1.5 hrs to the boarder and have the same issue, I know few folks in the US and may ship to them. I do have the paperwork from a 2.5R that was new 7 yrs ago, only ran one season that has a replacement form with a good deal that says some of the info is required for international customers. I plan to follow up this week and will let you know.

  7. #7
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    @Mike
    I use a UK supplier that’s just the prices I guess, when you shop around its sometimes cheaper to order from the US and pay the shipping if im honest. As far as engines most start at around the £100 price here you can get some for about £60 but they are makes like FORCE etc which tbf I have no idea about or experience with.
    Nah non of our plane engines are big enough for rings etc all just the same as the car but with smaller cooling heads and side exhausts. I do get what you mean about easier life, constant rpm…. But still 40 years and going strong some from before I was born and Im 33 lol yet a car one can pile in in no time.
    I have an original OS 18tm in a Tmaxx got it 2nd hand with no history and that runs amazing and how long has it been sins they stopped using that combination haha. Id fix the 3.3 but im just thinking how uncontrollable that would be in a 2wd rustler ive already b*stardised a wheelie bar on for 2.5.
    @stef66
    That’d be great if it works out and you could let me know that’s even more bonkers not offering it to someone on the same continent over a 1.5 hour difference in location hahaha

  8. #8
    RC Qualifier nebulous.cow's Avatar
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    I just got the 21tm for my revo and it's pretty awesome. I know it's crazy expensive, but it's an amazing motor for the money. And it's been out for a while, so not like dealers are unfamiliar with it either. It's definitely got more punch than the stock 3.3 even with stock resonator exhaust. You can always gear up if the motor has too much power, and get a little more speed.

    -Mike

  9. #9
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    Follow up, just got off the phone with Traxxas and they do offer both the power up and lifetime warranty to Canada, I asked "outside the US" and they said yes. The only variable will be the taxes and duty due at the boarder, my experience is sometimes its very little, others not so. Im getting 2 new 2.5R and 1 3.3 for $295 US including shipping, the hobby stores here want $249 Canadian for 1 - 2.5R !!

  10. #10
    RC Champion grizzly03's Avatar
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    Quote Originally Posted by stef66 View Post
    Follow up, just got off the phone with Traxxas and they do offer both the power up and lifetime warranty to Canada, I asked "outside the US" and they said yes. The only variable will be the taxes and duty due at the boarder, my experience is sometimes its very little, others not so. Im getting 2 new 2.5R and 1 3.3 for $295 US including shipping, the hobby stores here want $249 Canadian for 1 - 2.5R !!
    I'm glad it has worked out for you. Not a bad deal at all, except for possible duties.

  11. #11
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    Quote Originally Posted by stef66 View Post
    Follow up, just got off the phone with Traxxas and they do offer both the power up and lifetime warranty to Canada, I asked "outside the US" and they said yes. The only variable will be the taxes and duty due at the boarder, my experience is sometimes its very little, others not so. Im getting 2 new 2.5R and 1 3.3 for $295 US including shipping, the hobby stores here want $249 Canadian for 1 - 2.5R !!
    So after spending a bit of time and phone bill money talking tho traxxas USA they apparently wonít offer this to the UK even if Iím willing to pay shipping too and from 🤦*♂️ Just not something they offer apparently. Most they could suggest is posting to someone in the US, they then pay price + shipping with in the US then when they get it back post it again back to the UK 😂😂 what a load of Bollox.

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