TBI Oversize Powervalve Cover Installation- Two Stroke Performance

[@chestertownelectric6290]

How does it work?? At high revs the pressure waves travelling back and forth through the expansion chamber help to supercharge the cylinder, filling it with more fresh fuel/air than it would otherwise receive. This supercharging effect, and the extra power that results, is often what riders feel when they say a 2 stroke is “on the pipe” at higher revs. The downside of this phenomenon is that the same pressure waves that help to supercharge the cylinder at high revs actually make it harder for fresh charge to enter the cylinder at lower revs. This causes a drop in power at low/mid revs. To combat this some powervalve systems incorporate a ‘Torque Chamber’. A Torque Chamber is a chamber on the side or top of the cylinder which is opened and closed by the action of the powervalve. When the powervalve is closed or down, the chamber is open to the exhaust gasses. When the powervalve opens at high revs the chamber becomes closed to the exhaust gasses. At low revs, when the chamber is open, the pressure waves travelling through the expansion chamber enter the Torque Chamber and are dissipated somewhat, losing some of their strength. The reduction in the strength of these waves helps to improve the filling of the cylinder with fresh charge. Therefore, the Torque Chamber adds extra power down low by reducing the negative impact of the pipe in this rpm range. By adjusting the volume of the Torque Chamber we can further reduce the negative impact of the pipe at low revs, and increase power even more. This is how the TSP Oversize Powervalve cover helps to increase power at low revs (approx 3000-5000rpm). In order to find the ideal volume of the chamber we spent months dyno and track testing various designs until we settled on a design that made a noticeable improvement in low/mid torque.

[@myronmoso]

I just purchased one of these but haven't had a chance to install it yet. I was told by South Bay Motosports that now you just use all the stock bolts for the installation.

[@bretstephensen8821]

I installed one of these on my 24 KTM 300 Hardenduro. I am very pleased with the results.

[@barnescycle]

My OCD would have me looking for a stock bolt that length for sure.

[@SIcK_103]

Hi, any chance these might be available for the Sherco's?

[@russ66023]

Do you know what the internal volume is of the standard cover compared to your one? Thanks

[@al-ew3mj]

how does this give more power i dont understand its just a cover hmm thx very interested

[@chestertownelectric6290]

It adds more volume to the power valve / exhaust area. It must change the resonance, like a boost bottle. TSP: post some dyno runs.

[@TwoStrokePerformance]

There are dyno runs on the product listing...

[@DirtRider6512]

@@TwoStrokePerformance Is the graph showing rpm vs torque or hp? I assume torque.

[@andrewberg2361]

Nice product . Waiting for the new video on the installation of the IRK on a TPI 250 .😊

[@simsonschrauber05]

It is the same as on the 300

[@andrewberg2361]

​@@simsonschrauber05, there is a new procedure as the kit has changed slightly.

[@jimzigouris]

price tag?

[@MechShark]

120 USD

[@lukefrs1]

Installed one of these on my 24 300exc amd the engine management light has come on (5 lomg flashes) I've heard the cover can sometimes need a small amount taken away with a dremel??? Is this correct??? Thanks

[@sleeplesselkproductions8030]

My bike did the same thing. Did a powervalve reset, check engine light went away.

[@TwoStrokePerformance]

If you perform a powervavle reset it should stop the code from coming back. There were a very limited number of covers manufactured which 'may' have caused the PV to generate a fault code. Performing the PV reset will normally fix the issue.

[@lukefrs1]

@@TwoStrokePerformance have you had issues with the set screw fouling the PV cover??? I can see where it's been hitting???

[@ScottCarey-gl6wz]

Did you get to the bottom of this just installed one in my 2025 and on hard acceleration it throws the light on

[@saskracer1]

Does this sacrifice any top end? How would this work for a 300sx being used for MX with positive results?

[@TwoStrokePerformance]

Hi, no it doesn't sacrifice top end, however if you are riding faster stuff most of the time you wont notice much difference. The biggest gains are at low revs, approx 3500-5000 so if you are riding in that area a lot you will notice a big difference, but if youre mostly above 5000rpm you wont feel much.

[@baldknobby]

Any tuning changes needed with the ERM?

[@MechShark]

Nope.

[@grutzmac]

Can this be installed on a stock TBI without the TSP kit and receive the same or similar results?

[@TwoStrokePerformance]

Yes it can

[@SingleSpeederLife]

@@TwoStrokePerformance same increase in low down and mid power?

[@kraigvanderwyk1153]

Great idea. Now make it for bikes that actually need more bottom end like 200cc , 150, 125, 85cc.

[@TwoStrokePerformance]

Would love to but those motors dont have the 'Torque Chamber' design incorporated into their powervalve design.

[@booger65man]

I bought a TSP head for a 23 250 XC I was planning to build. I found a great deal and picked up a 300 XC a few weeks later after which I sold the 250. I emailed TSP and ask if I could exchange the 250 head for one for my 300. They never replied. I didn't think that it would be a big deal. I was wrong. I'll buy from companies that are easier to work with in the future.

[@jamesoso259]

Stop then bs tsp is super easy to work with and is south bay

[@booger65man]

You can characterize my experience and detailed explanation anyway you like. You can call me names and accuse me of anything you like. It does not change the voracity of my claims and I’ll allow the viewers to draw their own conclusions, including you.

[@booger65man]

TSP is not a company I would recommend. Last year I picked up a new XC 250. I ordered some parts including a TSP head, planning to build a bike over the winter. I then had an opportunity to pick up an xc300, which I did and subsequently sold the 250 still in the crate. I emailed TSP asking if I could exchange the head(still in the unopened box)for one for the 300. No reply. I emailed them again a week later stating I would pay any price difference as well as shipping both ways. Noreply. I emailed them a third time a couple of weeks later. No reply. They simply do not care about customer service.

[@TwoStrokePerformance]

Please stop spamming our videos with the same comment. We have responded to a previous comment from you several months ago asking for you to contact us with more details as we had no record of your email address or anyone contacting us via email with a story like this. We have not heard anything other than more anonymous comments on videos. The fact is we have no record of your story and no missed emails. Perhaps it was dealt with and you didnt like the outcome, or perhaps you were dealing with one of our distributors overseas? If you are serious about having this dealt with please provide a name, email address and purchase receipt and we will happily look into it. We would normally exchange a product with no questions if the purchase was within a recent timeframe and the goods and packaging were as new. Unfortunately we cant always be held responsible if you change your mind about a bike build, but we do take customer service very seriously and make significant efforts to keep the vast majority of our customers happy. You cant always please everyone though.

[@booger65man]

​@@TwoStrokePerformance I'm happy that you have finally responded. I will allow readers to determine if I am spamming or this is in fact an example of the sort of customer experience they can expect when dealing with SoutBay MotoPerformance. I have no reason to lie and nothing to gain other than helping others understand what happened in my case. I'm happy for all the customers that had a better experience. I am 58 years old and have ridden motorcycles practially my entire life. I raced on the professional level and have had more bikes than I can remember. There are 5 in my garage at this moment. I am decently successful and have no reason to quible over a couple hundred dollars here or there. It is why after sending you multiple emails I simply gave up and gave the head to a friend who had an xc250. There are others that parts for there motorcycles represent a significant investment and for those people, I would say, make your own decision as to whether I am spamming or sharing an accurate account of what happened with my experience. You certainly never replied to any of my emails and I have the reciepts to back that up. Not to my inbox, not to my spam folder, no reply period! I'm not going to share personal information on the internet and I have no desire nor reason to contact you directly as I have no need at this point to return or exhange the part I no longer have. You also did not ever reply to any comment I have made on YT regarding this until today. Trust me sir, had you reponded, I would have engaged you just as I am today. You are either a liar, have very poor memory or have confused me with someone else. I'll assume that latter and leave it to readers to interpret the tone of your response and the varacity of my experience. The only piece of info I will share is that the original email was sent on Sunday, April 21st, 2024 at 4:39 PM Mountain. If you track that down and respond, I will certainly respond back and confirm receipt. At this point sir, I have never recieved a reply to any of the emails I sent.

[@TwoStrokePerformance]

@@booger65man thanks for the detailed reply. It has highlighted the reason for our mutual frustration and finally gives us something to work with… you mentioned South Bay Moto Performance… South Bay is a distributor of ours in the USA and although we work closely together we are not the same business. We don’t have access to their emails or sales records. If you purchased from South Bay Moto then you did not purchase direct from us. This would explain why we have no record of your sale or emails. Steve at South Bay is renowned for excellent customer service and it is very surprising to hear your emails went unanswered. I will forward the details of your complaint and discuss with him further.

[@jamesoso259]

@@booger65manall you have to do is call south bay you dork. I’ve called them 7pm and they’ve picked up and answered questions for parts I didn’t even buy yet. Sounds like you’re incompetent

[@booger65man]

You can characterize my experience and detailed explanation anyway you like. You can call me names and accuse me of anything you like. It does not change the voracity of my claims and I’ll allow the viewers to draw their own conclusions, including you.

[@DirtRider6512]

Seems like some snake oil. I read the detail on the website and it does not in great detail say what is going on exactly.

[@TwoStrokePerformance]

Its not snake oil. Some 2 stroke engines have used these chambers as part of their powervalve design for decades. The old KTM 360/380 motors, and the GasGas (now Reiju) 250/300 motors are 2 examples of exactly the same system. KTM has brought back an old design in the new generation 250/300 motor. Our website gives a fairly clear explanation on how the cover works... here is the text... "At high revs the pressure waves travelling back and forth through the expansion chamber help to supercharge the cylinder, filling it with more fresh fuel/air than it would otherwise receive. This supercharging effect, and the extra power that results, is often what riders feel when they say a 2 stroke is “on the pipe” at higher revs. The downside of this phenomenon is that the same pressure waves that help to supercharge the cylinder at high revs actually make it harder for fresh charge to enter the cylinder at lower revs. This causes a drop in power at low/mid revs. To combat this some powervalve systems incorporate a ‘Torque Chamber’. A Torque Chamber is a chamber on the side or top of the cylinder which is opened and closed by the action of the powervalve. When the powervalve is closed or down, the chamber is open to the exhaust gasses. When the powervalve opens at high revs the chamber becomes closed to the exhaust gasses. At low revs, when the chamber is open, the pressure waves travelling through the expansion chamber enter the Torque Chamber and are dissipated somewhat, losing some of their strength. The reduction in the strength of these waves helps to improve the filling of the cylinder with fresh charge. Therefore, the Torque Chamber adds extra power down low by reducing the negative impact of the pipe in this rpm range. By adjusting the volume of the Torque Chamber we can further reduce the negative impact of the pipe at low revs, and increase power even more. This is how the TSP Oversize Powervalve cover helps to increase power at low revs (approx 3000-5000rpm). In order to find the ideal volume of the chamber we spent months dyno and track testing various designs until we settled on a design that made a noticeable improvement in low/mid torque."

[@strictlymitch]

S3 has been making a similar product for the shercos for a few years. Can tell you it 100% makes the bike nicer to ride Awesome to see TSP make their own version

[@devodar2579]

There is absolutely nothing that comes out of TSP that can be labeled or even that closely resembles snake oil. This company hits the high mark for solid performance and then some!!!

[@DirtRider6512]

@@strictlymitch I will only make one comment to that at what price? If you are a pro and need .5 more then spend the cash. $180.00 + shipping. If they were to show that 0.5 more torque would make significant difference to any rider. If you could see some sort of prospective of the real difference or gain from this modification. A quantitative view. The graph does show a difference but can you explain what that really means? Not some generic term more low end. More yes but quantify that.

[@stevenbusk539]

My Kawasaki KMX125 has the KIPS power valve system, which has a similar chamber that connects to the exhaust port duct. When the power valves are closed, this chamber is open to the exhaust port, and when the power valves open the auxiliary exhaust ports, the chamber is blocked off simultaneously. It definitely works on my bike in the 4000-6000rpm area. So the modern Enduro and MX bikes work the same way, with a multi function power valve. I've read that because the chamber is effectively a resonator to nullify the action of the wave energy in the pipe, it can only work optimally at one particular engine speed, but in practice the range where there is some degree of useful effect is spread over around 1000rpm. The same thing would apply with an inlet boost bottle, but I don't know if both systems would work together without interfering with each other?